SwiftUI 的新功能

2:51 - Swift Charts: Required models and extensions

import Foundation
import SwiftUI

// MARK: - Party Planner Models
enum PartyTask: String, Identifiable, CaseIterable, Hashable {
    case food = "Food"
    case music = "Music"
    case supplies = "Supplies"
    case invitations = "Invitations"
    case eventDetails = "Event Details"
    case activities = "Activities"
    case funProjection = "Fun Projection"
    case vips = "VIPs"
    case photosFilter = "Photos Filter"

    var name: String { rawValue }
  
   var color: Color {
       switch self {
       case .food:
            return palette[0]
       case .supplies:
            return palette[1]
       case .invitations:
            return palette[2]
       case .eventDetails:
            return palette[3]
       case .funProjection:
            return palette[4]
       case .activities:
            return palette[5]
       case .vips:
            return palette[6]
       case .music:
            return palette[7]
       case .photosFilter:
            return palette[8]
       }
    }

    var imageName: String {
        switch self {
        case .food:
            return "birthday.cake"
        case .supplies:
            return  "party.popper"
        case .invitations:
            return "envelope.open"
        case .eventDetails:
            return "calendar.badge.clock"
        case .funProjection:
            return "gauge.medium"
        case .activities:
            return "bubbles.and.sparkles"
        case .vips:
            return "person.2"
        case .music:
            return  "music.mic"
        case .photosFilter:
            return "camera.filters"
        }
    }

    var id: String { rawValue }

    var subtitle: String {
        switch self {
        case .food:
            return "Apps, 'Zerts and Cakes"
        case .supplies:
            return "Streamers, Plates, Cups"
        case .invitations:
            return "Sendable, Non-Transferable"
        case .eventDetails:
            return "Date, Duration, And Placement"
        case .funProjection:
            return "Beta — How Fun Will Your Party Be?"
        case .activities:
            return "Dancing, Paired Programing"
        case .vips:
            return "User Interactive Guests"
        case .music:
            return "Song Requests & Karaoke"
        case .photosFilter:
            return "Filtering and Mapping"
        }
    }

    var emoji: String {
        switch self {
        case .food:
            return "🎂"
        case .music:
            return "🎤"
        case .supplies:
            return "🎉"
        case .invitations:
            return "📨"
        case .eventDetails:
            return "🗓"
        case .funProjection:
            return "🧭"
        case .activities:
            return "💃"
        case .vips:
            return "⭐️"
        case .photosFilter:
            return "📸"
        }
    }
}

private let palette: [Color] = [
    Color(red: 0.73, green: 0.20, blue: 0.20),
    Color(red: 0.95, green: 0.66, blue: 0.24),
    Color(red: 0.14, green: 0.29, blue: 0.49),
    Color(red: 0.46, green: 0.76, blue: 0.67),
    Color(red: 0.30, green: 0.33, blue: 0.22),
    Color(red: 0.49, green: 0.55, blue: 0.64),
    Color(red: 0.92, green: 0.53, blue: 0.30),
    Color(red: 0.20, green: 0.45, blue: 0.55),
    Color(red: 0.41, green: 0.45, blue: 0.45),
    Color(red: 0.87, green: 0.67, blue: 0.61)
]

// MARK: - Swift Charts Models

struct RemainingPartyTask: Identifiable {
    let category: PartyTask
    let date: Date
    let remainingCount: Int

    let id = UUID()
}

let remainingSupplies: [RemainingPartyTask] = [
    RemainingPartyTask(category: .supplies, date: .daysAgo(4), remainingCount: 10),
    RemainingPartyTask(category: .supplies, date: .daysAgo(3), remainingCount: 11),
    RemainingPartyTask(category: .supplies, date: .daysAgo(2), remainingCount: 9),
    RemainingPartyTask(category: .supplies, date: .daysAgo(1), remainingCount: 4),
    RemainingPartyTask(category: .supplies, date: .daysAgo(0), remainingCount: 1),
]

let remainingInvitations: [RemainingPartyTask] = [
    RemainingPartyTask(category: .invitations, date: .daysAgo(4), remainingCount: 14),
    RemainingPartyTask(category: .invitations, date: .daysAgo(3), remainingCount: 13),
    RemainingPartyTask(category: .invitations, date: .daysAgo(2), remainingCount: 11),
    RemainingPartyTask(category: .invitations, date: .daysAgo(1), remainingCount: 6),
    RemainingPartyTask(category: .invitations, date: .daysAgo(0), remainingCount: 4),
]

let remainingActivities: [RemainingPartyTask] = [
    RemainingPartyTask(category: .activities, date: .daysAgo(4), remainingCount: 6),
    RemainingPartyTask(category: .activities, date: .daysAgo(3), remainingCount: 7),
    RemainingPartyTask(category: .activities, date: .daysAgo(2), remainingCount: 4),
    RemainingPartyTask(category: .activities, date: .daysAgo(1), remainingCount: 2),
    RemainingPartyTask(category: .activities, date: .daysAgo(0), remainingCount: 1),
]

let remainingVenue: [RemainingPartyTask] = [
    RemainingPartyTask(category: .eventDetails, date: .daysAgo(4), remainingCount: 4),
    RemainingPartyTask(category: .eventDetails, date: .daysAgo(3), remainingCount: 5),
    RemainingPartyTask(category: .eventDetails, date: .daysAgo(2), remainingCount: 7),
    RemainingPartyTask(category: .eventDetails, date: .daysAgo(1), remainingCount: 4),
    RemainingPartyTask(category: .eventDetails, date: .daysAgo(0), remainingCount: 2)
]

let partyTasksRemaining: [RemainingPartyTask] = [remainingVenue,
                                                remainingActivities,
                                                remainingInvitations,
                                                remainingSupplies
].flatMap { $0 }

// MARK: Date Utilities

extension Date {
    static func daysAgo(_ daysAgo: Int) -> Date {
        Calendar.current.date(byAdding: .day, value: -daysAgo, to: Date())!
    }

    func daysEqual(_ other: Date) -> Bool {
        Calendar.current.dateComponents([.day], from: self, to: other).day == 0
    }
}

extension Date {
    static let wwdc22: Date = DateComponents(
        calendar: .autoupdatingCurrent,
        timeZone: TimeZone(identifier: "PST"),
        year: 2022,
        month: 6,
        day: 6,
        hour: 9,
        minute: 41,
        second: 00).date!
}

2:56 - Swift Charts: Bar Chart 1

Chart(partyTasksRemaining) {
    BarMark(
        x: .value("Date", $0.date, unit: .day),
        y: .value("Tasks Remaining", $0.remainingCount)
    )
}
.padding()

3:33 - Swift Charts: Bar chart 2

var body: some View {
    Chart(partyTasksRemaining) {
        BarMark(
            x: .value("Date", $0.date, unit: .day),
            y: .value("Tasks Remaining", $0.remainingCount)
        )
    }
    .padding()
}

3:53 - Swift Charts: LineMark

var body: some View {
    Chart(partyTasksRemaining) {
        LineMark(
            x: .value("Date", $0.date, unit: .day),
            y: .value("Tasks Remaining", $0.remainingCount)
        )
        .foregroundStyle(by: .value("Category", $0.category))
    }
    .padding()
}

4:08 - Swift Charts: Line Chart with Symbols

var body: some View {
    Chart(partyTasksRemaining) {
        LineMark(
            x: .value("Date", $0.date, unit: .day),
            y: .value("Tasks Remaining", $0.remainingCount)
        )
        .foregroundStyle(by: .value("Category", $0.category))
        .symbol(by: .value("Category", $0.category))
    }
    .padding()
}

4:39 - Swift Charts: Annotations

var body: some View {
    Chart {
        ForEach(partyTasksRemaining) { task in
            LineMark(
                x: .value("Date", task.date, unit: .day),
                y: .value("Tasks Remaining", task.remainingCount)
            )
            .foregroundStyle(by: .value("Category", task.category))
            .symbol(by: .value("Category", task.category))
            .annotation(position: .leading) {
                Text("\(task.category.emoji)")
            }
        }

        RuleMark(y: .value("Value", 5))
            .foregroundStyle(.red)
            .lineStyle(StrokeStyle(lineWidth: 2.0, dash: [4, 5]))
            .annotation(position: .top, alignment: .trailing) {
                VStack(alignment: .trailing) {
                    Text("Today's Goal")
                    Text("Status: ✔︎")
                }
                .font(.caption)
                .foregroundColor(.gray)
                .padding(.trailing, 2)
            }
    }
}

6:15 - Food Models

import Foundation

// MARK: Food Models

/// A model representing a food with a price and quantity.
struct FoodItem: Hashable, Identifiable, Codable, Equatable {
    let emoji: String
    let name: String
    var description: String = ""
    let price: Decimal
    var quantity: Int = 0
    var id: String { name }
}

let donut = FoodItem(emoji: "🍩", name: "Doughnut", description: "Yeast, Old-fashioned, Cake, and the dubious Apple Fritter", price: 2.35, quantity: 6)
let moonCake = FoodItem(emoji: "🥮", name: "Moon Cake", description: "Lotus seed paste — plenty of crust", price: 2.20, quantity: 4)
let shavedIce = FoodItem(emoji: "🍧", name: "Shaved Ice", description: "Shave your own ice!", price: 3.25, quantity: 1)
let cupcake = FoodItem(emoji: "🧁", name: "Cupcake", description: "Also goes by the name Cake Nano", price: 4.00, quantity: 5)
let flan = FoodItem(emoji: "🍮", name: "Flan", description: "What's in a flan? That which we call milk, eggs, and sugar by any other name would taste just as sweet.", price: 6.50, quantity: 2)
let taffy = FoodItem(emoji: "🍬", name: "Taffy", description: "Freshwater, actually.", price: 1.00, quantity: 11)
let cake = FoodItem(emoji: "🎂", name: "Cake Cake", description: "The real deal", price: 15.00, quantity: 1)
let cookie = FoodItem(emoji: "🍪", name: "Cookie Cake", description: "The ultimate dessert", price: 4.30, quantity: 1)

let relatedFoods = [donut, moonCake, shavedIce, cupcake, flan, taffy, cake, cookie]

extension Array where Element: Equatable {

    /// A quick-and-dirty way of getting a random few elements from an Array that don't include a single,
    /// particular element.
    /// - Parameters:
    ///   - count: The number of desired random elements, must be less than `Array.count`
    ///   - except: Filter out this particular element    
    func random(_ count: Int, except: Element) -> [Element] {
        assert(count >= count)
        var copy = self
        copy.shuffle()
        copy.removeAll(where: { $0 == except })
        return Array(copy[0..<count])
    }
}

let partyFoods = [
    FoodItem(emoji: "🍨", name: "Ice Cream",
             price: 3.50, quantity: 4),
    flan,
    taffy,
    donut,
    FoodItem(emoji: "🍉", name: "Watermelon",
             price: 3.65, quantity: 1),
    FoodItem(emoji: "🍒", name: "Cherries",
             price: 8.00, quantity: 1),
    cupcake,
    cookie,
    FoodItem(emoji: "🍥", name: "Fish Cake",
             price: 5.00, quantity: 2),
    moonCake,
    cake,
    FoodItem(emoji: "🍘", name: "Rice Cracker",
             price: 0.25, quantity: 16),
    FoodItem(emoji: "🥨", name: "Pretzels",
             price: 3.00, quantity: 3),
    shavedIce,
    FoodItem(emoji: "🥧", name: "Apple Pie",
             price: 4.10, quantity: 1)
]

6:21 - NavigationStack with view-based NavigationLinks

// MARK: NavigationStack with View-based NavigationLinks

struct FoodsListView: View {
    fileprivate var foodItems = partyFoods
    @State private var selectedFoodItems: [FoodItem] = []

    var body: some View {
        NavigationStack {
            List(foodItems) { item in
                NavigationLink {
                    FoodDetailView(item: item)
                } label: {
                    FoodRow(food: item)
                }
            }
            .navigationTitle("Party Food")

        }
    }
}

struct FoodRow: View {
    let food: FoodItem

    var body: some View {
        HStack {
            Text(food.emoji)
                .font(.system(size: 15))
                .foregroundStyle(.secondary)
            Text(food.name)
                .font(.caption)
                .bold()
            Spacer()
            Text("\(food.quantity)")
        }
    }
}

struct FoodDetailView: View {
    let item: FoodItem

    var body: some View {
        ScrollView {
            VStack {
                HStack {
                    Text(item.emoji)
                        .font(.system(size: 30))
                    Text(item.name)
                        .font(.title3)
                }
                .padding(.bottom, 4)
                Text(item.description)
                    .font(.caption)
                Divider()
                RelatedFoodsView(relatedFoods: relatedFoods.random(3, except: item))
            }
        }
    }
}

struct RelatedFoodsView: View {
    @State var relatedFoods: [FoodItem]

    var body: some View {
        VStack {
            Text("Related Foods")
                .background(.background, in: RoundedRectangle(cornerRadius: 2))
            HStack {
                ForEach(relatedFoods) { food in                    
                    NavigationLink {
                        FoodDetailView(item: food)
                    } label: { Text(food.emoji) }
                }
            }
        }
    }
}

6:51 - NavigationStack with value-based NavigationLinks

// MARK: NavigationStack with Value-based Navigation Links

struct FoodsListView: View {
    fileprivate var foodItems = partyFoods
    @State private var selectedFoodItems: [FoodItem] = []

    var body: some View {
        NavigationStack(path: $selectedFoodItems) {
            List(foodItems) { item in
                NavigationLink(value: item) {
                    FoodRow(food: item)
                }
            }
            .navigationTitle("Party Food")
            .navigationDestination(for: FoodItem.self) { item in
                FoodDetailView(item: item, path: $selectedFoodItems)
            }
        }
    }
}

struct FoodDetailView: View {
    let item: FoodItem
    @Binding var path: [FoodItem]

    var body: some View {
        ScrollView {
            VStack {
                HStack {
                    Text(item.emoji)
                        .font(.system(size: 30))
                    Text(item.name)
                        .font(.title3)
                }
                .padding(.bottom, 4)
                Text(item.description)
                    .font(.caption)
                Divider()
                RelatedFoodsView(relatedFoods: relatedFoods.random(3, except: item))
                if path.count > 1 {
                    Button("Back to First Item") { path.removeSubrange(1...) }
                }
            }
        }
    }
}

struct RelatedFoodsView: View {
    @State var relatedFoods: [FoodItem]

    var body: some View {
        VStack {
            Text("Related Foods")
                .background(.background, in: RoundedRectangle(cornerRadius: 2))
            HStack {
                ForEach(relatedFoods) { food in
                    NavigationLink(value: food) {
                        Text(food.emoji)
                    }
                }
            }
        }
    }
}

8:16 - NavigationSplitView

// MARK: NavigationSplitView Demo

struct PartyPlannerHome: View {
    @State private var selectedTask: PartyTask?

    var body: some View {
        NavigationSplitView {
            List(PartyTask.allCases, selection: $selectedTask) { task in
                NavigationLink(value: task) {
                    TaskLabel(task: task)
                }
						    .listItemTint(task.color)
            }
        } detail: {
            selectedTask.flatMap { $0.color } ?? .white
        }
    }
}

struct TaskLabel: View {
    let task: PartyTask

    var body: some View {
        Label {
            VStack(alignment: .leading) {
                Text(task.name)
                Text(task.subtitle)
                    .font(.footnote)
                    .foregroundStyle(.secondary)
            }
        } icon: {
            Image(systemName: task.imageName)
                .symbolVariant(.circle.fill)
        }
    }
}

9:13 - Navigation split and stack composition

struct PartyPlannerHome: View {
    @State private var selectedTask: PartyTask?

    var body: some View {
        NavigationSplitView {
            List(PartyTask.allCases, selection: $selectedTask) { task in
                NavigationLink(value: task) {
                    TaskLabel(task: task)
                }
                .listItemTint(task.color)
            }
        } detail: {
            if case .food = selectedTask {
                FoodsListView()
            } else {
                selectedTask.flatMap { $0.color } ?? .white
            }
        }
    }
}

10:10 - Window

@main
struct PartyPlanner: App {
    var body: some Scene {
        WindowGroup("Party Planner") {
            PartyPlannerHome()
        }

        Window("Party Budget", id: "budget") {
            Text("Budget View")
        }
        .keyboardShortcut("0")
    }
}

10:42 - Open window

struct DetailView: View {
    @Environment(\.openWindow) var openWindow

    var body: some View {
        Text("Detail View")
            .toolbar {
                Button {
                    openWindow(id: "budget")
                } label: {
                    Image(systemName: "dollarsign")
                }
            }
    }
}

11:00 - Window customizations

@main
struct PartyPlanner: App {
    var body: some Scene {
        WindowGroup("Party Planner") {
            PartyPlannerHome()
        }

        Window("Party Budget", id: "budget") {
            Text("Budget View")
        }
        .keyboardShortcut("0")
        .defaultPosition(.topLeading)
        .defaultSize(width: 220, height: 250)
    }
}

11:47 - Resizable sheets

struct PartyPlannerHome: View {
    @State private var selectedTask: PartyTask?
    @State private var presented: Bool = false

    var body: some View {
        NavigationSplitView {
            List(PartyTask.allCases, selection: $selectedTask) { task in
                NavigationLink(value: task) {
                    TaskLabel(task: task)
                }
                .listItemTint(task.color)
            }
        } detail: {
            if case .food = selectedTask {
                FoodsListView()
            } else {
                selectedTask.flatMap { $0.color } ?? .white
            }
        }
        .sheet(isPresented: $presented) {
            Text("Budget View")
                .presentationDetents([.height(250), .medium])
                .presentationDragIndicator(.visible)
        }
    }
}

12:51 - Menu bar extras

@main
struct PartyPlanner: App {
    var body: some Scene {
        Window("Party Budget", id: "budget") {
            Text("Budget View")
        }

        MenuBarExtra("Bulletin Board", systemImage: "quote.bubble") {
            BulletinBoard()
        }
        .menuBarExtraStyle(.window)
    }
}



private let allPosts: [String] = [
    "Did you know: On your third birthday, you are celebrating your 4.0 release.",
]

struct BulletinBoard: View {

    @State var currentPostIndex: Int = 0

    var currentPost: String {
        allPosts[currentPostIndex]
    }

    var body: some View {
        VStack(spacing: 16) {

            VStack(spacing: 12) {
                HStack(alignment: .firstTextBaseline) {
                    Text("“")
                        .font(.custom("Helvetica", size: 50).bold())
                        .baselineOffset(-23)
                        .foregroundStyle(.tertiary)

                    Text("Party Bulletin Board")
                        .font(.headline.weight(.semibold))
                        .foregroundStyle(.secondary)

                    Spacer()

                    Text("June 6, 2022")
                        .font(.headline.weight(.regular))
                        .foregroundStyle(.secondary)
                }
                .frame(height: 20)


                Text(currentPost)
                    .font(.system(size: 18))
                    .multilineTextAlignment(.center)
            }
            .padding(.bottom, 4)

            Divider()

            HStack {
                Button {

                } label: {
                    Label("Calendar", systemImage: "calendar")
                }
                Button {
                    currentPostIndex = (currentPostIndex + 1) % allPosts.count
                } label: {
                    Text("Previous")
                        .frame(maxWidth: .infinity)
                }

                ShareLink(items: [currentPost])
            }
            .labelStyle(.iconOnly)
            .controlSize(.large)
        }
        .padding(16)
    }
}

12:58 - Menu bar extra app

@main
struct MessageBoard: App {
    var body: some Scene {
        MenuBarExtra("Bulletin Board", systemImage: "quote.bubble") {
            BulletinBoard()
        }
        .menuBarExtraStyle(.window)
    }
}

14:25 - Grouped forms

struct ContentView: View {
    enum Theme: String, CaseIterable, Identifiable {
        var id: String { self.rawValue }
        case blue, gold, black, white

        var swatch: some View {
            Circle()
                .fill(color)
                .overlay {
                    Circle().stroke(.tertiary)
                }
                .frame(width: 15, height: 15)
        }

        var color: Color {
            switch self {
            case .blue: return .blue
            case .gold: return .yellow
            case .black: return .black
            case .white: return .white
            }
        }
    }

    enum ColorScheme: String {
        case light, dark
    }

    enum Decoration: String, CaseIterable {
        case balloon, confetti, inflatables, noisemakers, all, none
    }

    private let address = "One Apple Park Way"

    @State private var date: Date = DateComponents(
        calendar: .current, timeZone: .current, year: 2022, month: 6, day: 6
    ).date!
    @State private var eventDescription: String =
        "Come and join us celebrate SwiftUI's birthday party!\n🎉🎂"

    @State private var scheme: ColorScheme = .light
    @State private var accent: Theme = .blue
    @State private var extraGuests = false
    @State private var spacesCount: Float = 2

    @State private var includeBalloons = false
    @State private var includeConfetti = false
    @State private var includeInflatables = false
    @State private var includeBlowers = false

    @State private var selectedDecorations: [Decoration] = []
    @State private var decorationThemes: [Decoration: Theme] = [
        .balloon : .blue,
        .confetti: .gold,
        .inflatables: .black,
        .noisemakers: .white,
        .none: .black
    ]

    private var themes: [Binding<Theme>] {
        if selectedDecorations.count == 0 {
            return [Binding($decorationThemes[.none])!]
        }
        return selectedDecorations.compactMap {
            Binding($decorationThemes[$0])
        }
    }

    var body: some View {
        Form {
            Section {
                LabeledContent("Location", value: address)
                DatePicker("Date", selection: $date)
                TextField("Description", text: $eventDescription, axis: .vertical)
                    .lineLimit(3, reservesSpace: true)
            }

            Section("Vibe") {
                Picker("Accent color", selection: $accent) {
                    ForEach(Theme.allCases) { theme in
                        Text(theme.rawValue.capitalized).tag(theme)
                    }
                }
                Picker("Color scheme", selection: $scheme) {
                    Text("Light").tag(ColorScheme.light)
                    Text("Dark").tag(ColorScheme.dark)
                }
                #if os(macOS)
                .pickerStyle(.inline)
                #endif
                Toggle(isOn: $extraGuests) {
                    Text("Allow extra guests")
                    Text("The more the merrier!")
                }
                if extraGuests {
                    Stepper("Guests limit", value: $spacesCount, format: .number)
                }
            }

            Section("Decorations") {
                Section {
                    List(selection: $selectedDecorations) {
                        DisclosureGroup {
                            HStack {
                                Toggle("Balloons 🎈", isOn: $includeBalloons)
                                Spacer()
                                decorationThemes[.balloon].map { $0.swatch }
                            }
                            .tag(Decoration.balloon)

                            HStack {
                                Toggle("Confetti 🎊", isOn: $includeConfetti)
                                Spacer()
                                decorationThemes[.confetti].map { $0.swatch }
                            }
                            .tag(Decoration.confetti)

                            HStack {
                                Toggle("Inflatables 🪅", isOn: $includeInflatables)
                                Spacer()
                                decorationThemes[.inflatables].map { $0.swatch }
                            }
                            .tag(Decoration.inflatables)

                            HStack {
                                Toggle("Party Horns 🥳", isOn: $includeBlowers)
                                Spacer()
                                decorationThemes[.noisemakers].map { $0.swatch }
                            }
                            .tag(Decoration.noisemakers)
                        } label: {
                            Toggle("All Decorations", isOn: [
                                $includeBalloons, $includeConfetti,
                                $includeInflatables, $includeBlowers
                            ])
                            .tag(Decoration.all)
                        }
                        #if os(macOS)
                        .toggleStyle(.checkbox)
                        #endif
                    }

                    Picker("Decoration theme", selection: themes) {
                        Text("Blue").tag(Theme.blue)
                        Text("Black").tag(Theme.black)
                        Text("Gold").tag(Theme.gold)
                        Text("White").tag(Theme.white)
                    }
                    #if os(macOS)
                    .pickerStyle(.radioGroup)
                    #endif
                }
            }

        }
        .formStyle(.grouped)
    }
}

15:45 - Grouped forms with LabeledContent wrapping a view.

struct ContentView: View {
    enum Theme: String, CaseIterable, Identifiable {
        var id: String { self.rawValue }
        case blue, gold, black, white

        var swatch: some View {
            Circle()
                .fill(color)
                .overlay {
                    Circle().stroke(.tertiary)
                }
                .frame(width: 15, height: 15)
        }

        var color: Color {
            switch self {
            case .blue: return .blue
            case .gold: return .yellow
            case .black: return .black
            case .white: return .white
            }
        }
    }

    enum ColorScheme: String {
        case light, dark
    }

    enum Decoration: String, CaseIterable {
        case balloon, confetti, inflatables, noisemakers, all, none
    }

    private let location = Location(
        firstLine: "One Apple Park Way", secondLine: "Cupertino, CA 95014")

    @State private var date: Date = DateComponents(
        calendar: .current, timeZone: .current, year: 2022, month: 6, day: 6
    ).date!
    @State private var eventDescription: String =
        "Come and join us celebrate SwiftUI's birthday party!\n🎉🎂"

    @State private var scheme: ColorScheme = .light
    @State private var accent: Theme = .blue
    @State private var extraGuests = false
    @State private var spacesCount: Float = 2

    @State private var includeBalloons = false
    @State private var includeConfetti = false
    @State private var includeInflatables = false
    @State private var includeBlowers = false

    @State private var selectedDecorations: [Decoration] = []
    @State private var decorationThemes: [Decoration: Theme] = [
        .balloon : .blue,
        .confetti: .gold,
        .inflatables: .black,
        .noisemakers: .white,
        .none: .black
    ]

    private var themes: [Binding<Theme>] {
        if selectedDecorations.count == 0 {
            return [Binding($decorationThemes[.none])!]
        }
        return selectedDecorations.compactMap {
            Binding($decorationThemes[$0])
        }
    }

    var body: some View {
        Form {
            Section {
                LabeledContent("Location") {
                    AddressView(location)
                }
                DatePicker("Date", selection: $date)
                TextField("Description", text: $eventDescription, axis: .vertical)
                    .lineLimit(3, reservesSpace: true)
            }

            Section("Vibe") {
                Picker("Accent color", selection: $accent) {
                    ForEach(Theme.allCases) { accent in
                        Text(accent.rawValue.capitalized).tag(accent)
                    }
                }
                Picker("Color scheme", selection: $scheme) {
                    Text("Light").tag(ColorScheme.light)
                    Text("Dark").tag(ColorScheme.dark)
                }
                #if os(macOS)
                .pickerStyle(.inline)
                #endif
                Toggle(isOn: $extraGuests) {
                    Text("Allow extra guests")
                    Text("The more the merrier!")
                }
                if extraGuests {
                    Stepper("Guests limit", value: $spacesCount, format: .number)
                }
            }

            Section("Decorations") {
                Section {
                    List(selection: $selectedDecorations) {
                        DisclosureGroup {
                            HStack {
                                Toggle("Balloons 🎈", isOn: $includeBalloons)
                                Spacer()
                                decorationThemes[.balloon].map { $0.swatch }
                            }
                            .tag(Decoration.balloon)

                            HStack {
                                Toggle("Confetti 🎊", isOn: $includeConfetti)
                                Spacer()
                                decorationThemes[.confetti].map { $0.swatch }
                            }
                            .tag(Decoration.confetti)

                            HStack {
                                Toggle("Inflatables 🪅", isOn: $includeInflatables)
                                Spacer()
                                decorationThemes[.inflatables].map { $0.swatch }
                            }
                            .tag(Decoration.inflatables)

                            HStack {
                                Toggle("Party Horns 🥳", isOn: $includeBlowers)
                                Spacer()
                                decorationThemes[.noisemakers].map { $0.swatch }
                            }
                            .tag(Decoration.noisemakers)
                        } label: {
                            Toggle("All Decorations", isOn: [
                                $includeBalloons, $includeConfetti,
                                $includeInflatables, $includeBlowers
                            ])
                            .tag(Decoration.all)
                        }
                        #if os(macOS)
                        .toggleStyle(.checkbox)
                        #endif
                    }

                    Picker("Decoration theme", selection: themes) {
                        Text("Blue").tag(Theme.blue)
                        Text("Black").tag(Theme.black)
                        Text("Gold").tag(Theme.gold)
                        Text("White").tag(Theme.white)
                    }
                    #if os(macOS)
                    .pickerStyle(.radioGroup)
                    #endif
                }
            }

        }
        .formStyle(.grouped)
    }
}


struct AddressView: View {
    private let location: Location

    init(_ location: Location) {
        self.location = location
    }

    var body: some View {
        VStack {
            Text(location.firstLine)
            Text(location.secondLine)
        }
    }
}

struct Location {
    let firstLine: String
    let secondLine: String
}

17:06 - Multiline text fields

struct ContentView: View {
    @State private var activityDates: Set<DateComponents> = [
        DateComponents(calendar: .current, year: 2022, month: 6, day: 6),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 9),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 10)
    ]
    @State private var title: String = .init()
    @State private var description: String = """
                Join us, and let's force unwrap SwiftUl's
                birthday presents. Note that although
                this activity is optional, we may have
                guards at the entry.
                """

    var body: some View {
        NavigationStack {
            Form {
                Section {
                    TextField("Title", text: $title)
                    TextField("Description", text: $description, axis: .vertical)
                }
                Section("Dates") {
                    MultiDatePicker("Activities Dates", selection: $activityDates)
                }
            }
            .navigationTitle("New Activity")
            .toolbar {
                Button("Save") {}
            }
        }
    }
}

17:20 - Multiline text fields with line limit

struct ContentView: View {
    @State private var activityDates: Set<DateComponents> = [
        DateComponents(calendar: .current, year: 2022, month: 6, day: 6),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 9),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 10)
    ]
    @State private var title: String = .init()
    @State private var description: String = """
                Join us, and let's force unwrap SwiftUl's
                birthday presents. Note that although
                this activity is optional, we may have
                guards at the entry.
                """

    var body: some View {
        NavigationStack {
            Form {
                Section {
                    TextField("Title", text: $title)
                    TextField("Description", text: $description, axis: .vertical)
                  		.lineLimit(5)
                }
                Section("Dates") {
                    MultiDatePicker("Activities Dates", selection: $activityDates)
                }
            }
            .navigationTitle("New Activity")
            .toolbar {
                Button("Save") {}
            }
        }
    }
}

17:23 - Multiline text fields with line limit range

struct ContentView: View {
    @State private var activityDates: Set<DateComponents> = [
        DateComponents(calendar: .current, year: 2022, month: 6, day: 6),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 9),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 10)
    ]
    @State private var title: String = .init()
    @State private var description: String = """
                Join us, and let's force unwrap SwiftUl's
                birthday presents. Note that although
                this activity is optional, we may have
                guards at the entry.
                """

    var body: some View {
        NavigationStack {
            Form {
                Section {
                    TextField("Title", text: $title)
                    TextField("Description", text: $description, axis: .vertical)
                  		.lineLimit(5...10)
                }
                Section("Dates") {
                    MultiDatePicker("Activities Dates", selection: $activityDates)
                }
            }
            .navigationTitle("New Activity")
            .toolbar {
                Button("Save") {}
            }
        }
    }
}

17:40 - MultiDatePicker

struct ContentView: View {
    @State private var activityDates: Set<DateComponents> = [
        DateComponents(calendar: .current, year: 2022, month: 6, day: 6),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 9),
        DateComponents(calendar: .current, year: 2022, month: 6, day: 10)
    ]
    @State private var title: String = .init()
    @State private var description: String = """
                Join us, and let's force unwrap SwiftUl's
                birthday presents. Note that although
                this activity is optional, we may have
                guards at the entry.
                """

    var body: some View {
        NavigationStack {
            Form {
                Section {
                    TextField("Title", text: $title)
                    TextField("Description", text: $description, axis: .vertical)
                }
                Section("Dates") {
                    MultiDatePicker("Activities Dates", selection: $activityDates)
                }
            }
            .navigationTitle("New Activity")
            .toolbar {
                Button("Save") {}
            }
        }
    }
}

18:10 - Mixed-state toggles & pickers

struct ContentView: View {
    enum Theme: String, CaseIterable, Identifiable {
        var id: String { self.rawValue }
        case blue, gold, black, white

        var swatch: some View {
            Circle()
                .fill(color)
                .overlay {
                    Circle().stroke(.tertiary)
                }
                .frame(width: 15, height: 15)
        }

        var color: Color {
            switch self {
            case .blue: return .blue
            case .gold: return .yellow
            case .black: return .black
            case .white: return .white
            }
        }
    }

    enum ColorScheme: String {
        case light, dark
    }

    enum Decoration: String, CaseIterable {
        case balloon, confetti, inflatables, noisemakers, all, none
    }

    private let location = Location(
        firstLine: "One Apple Park Way", secondLine: "Cupertino, CA 95014")

    @State private var date: Date = DateComponents(
        calendar: .current, timeZone: .current, year: 2022, month: 6, day: 6
    ).date!
    @State private var eventDescription: String =
        "Come and join us celebrate SwiftUI's birthday party!\n🎉🎂"

    @State private var scheme: ColorScheme = .light
    @State private var accent: Theme = .blue
    @State private var extraGuests = false
    @State private var spacesCount: Float = 2

    @State private var includeBalloons = false
    @State private var includeConfetti = false
    @State private var includeInflatables = false
    @State private var includeBlowers = false

    @State private var selectedDecorations: [Decoration] = []
    @State private var decorationThemes: [Decoration: Theme] = [
        .balloon : .blue,
        .confetti: .gold,
        .inflatables: .black,
        .noisemakers: .white,
        .none: .black
    ]

    private var themes: [Binding<Theme>] {
        if selectedDecorations.count == 0 {
            return [Binding($decorationThemes[.none])!]
        }
        return selectedDecorations.compactMap {
            Binding($decorationThemes[$0])
        }
    }

    var body: some View {
        Form {
            Section {
                LabeledContent("Location") {
                    AddressView(location)
                }
                DatePicker("Date", selection: $date)
                TextField("Description", text: $eventDescription, axis: .vertical)
                    .lineLimit(3, reservesSpace: true)
            }

            Section("Vibe") {
                Picker("Accent color", selection: $accent) {
                    ForEach(Theme.allCases) { accent in
                        Text(accent.rawValue.capitalized).tag(accent)
                    }
                }
                Picker("Color scheme", selection: $scheme) {
                    Text("Light").tag(ColorScheme.light)
                    Text("Dark").tag(ColorScheme.dark)
                }
                #if os(macOS)
                .pickerStyle(.inline)
                #endif
                Toggle(isOn: $extraGuests) {
                    Text("Allow extra guests")
                    Text("The more the merrier!")
                }
                if extraGuests {
                    Stepper("Guests limit", value: $spacesCount, format: .number)
                }
            }

            Section("Decorations") {
                Section {
                    List(selection: $selectedDecorations) {
                        DisclosureGroup {
                            HStack {
                                Toggle("Balloons 🎈", isOn: $includeBalloons)
                                Spacer()
                                decorationThemes[.balloon].map { $0.swatch }
                            }
                            .tag(Decoration.balloon)

                            HStack {
                                Toggle("Confetti 🎊", isOn: $includeConfetti)
                                Spacer()
                                decorationThemes[.confetti].map { $0.swatch }
                            }
                            .tag(Decoration.confetti)

                            HStack {
                                Toggle("Inflatables 🪅", isOn: $includeInflatables)
                                Spacer()
                                decorationThemes[.inflatables].map { $0.swatch }
                            }
                            .tag(Decoration.inflatables)

                            HStack {
                                Toggle("Party Horns 🥳", isOn: $includeBlowers)
                                Spacer()
                                decorationThemes[.noisemakers].map { $0.swatch }
                            }
                            .tag(Decoration.noisemakers)
                        } label: {
                            Toggle("All Decorations", isOn: [
                                $includeBalloons, $includeConfetti,
                                $includeInflatables, $includeBlowers
                            ])
                            .tag(Decoration.all)
                        }
                        #if os(macOS)
                        .toggleStyle(.checkbox)
                        #endif
                    }

                    Picker("Decoration theme", selection: themes) {
                        Text("Blue").tag(Theme.blue)
                        Text("Black").tag(Theme.black)
                        Text("Gold").tag(Theme.gold)
                        Text("White").tag(Theme.white)
                    }
                    #if os(macOS)
                    .pickerStyle(.radioGroup)
                    #endif
                }
            }

        }
        .formStyle(.grouped)
    }
}


struct AddressView: View {
    private let location: Location

    init(_ location: Location) {
        self.location = location
    }

    var body: some View {
        VStack {
            Text(location.firstLine)
            Text(location.secondLine)
        }
    }
}

struct Location {
    let firstLine: String
    let secondLine: String
}

18:53 - ButtonStyle composition & Steppers

struct ContentView: View {
    enum Theme: String, CaseIterable, Identifiable {
        var id: String { self.rawValue }
        case blue, gold, black, white

        var swatch: some View {
            Circle()
                .fill(color)
                .overlay {
                    Circle().stroke(.tertiary)
                }
                .frame(width: 15, height: 15)
        }

        var color: Color {
            switch self {
            case .blue: return .blue
            case .gold: return .yellow
            case .black: return .black
            case .white: return .white
            }
        }
    }

    enum ColorScheme: String {
        case light, dark
    }

    enum Decoration: String, CaseIterable {
        case balloon, confetti, inflatables, noisemakers, all, none
    }

    private let location = Location(
        firstLine: "One Apple Park Way", secondLine: "Cupertino, CA 95014")

    @State private var date: Date = DateComponents(
        calendar: .current, timeZone: .current, year: 2022, month: 6, day: 6
    ).date!
    @State private var eventDescription: String =
        "Come and join us celebrate SwiftUI's birthday party!\n🎉🎂"

    @State private var scheme: ColorScheme = .light
    @State private var accent: Theme = .blue
    @State private var extraGuests = false
    @State private var spacesCount: Float = 2

    @State private var includeBalloons = false
    @State private var includeConfetti = false
    @State private var includeInflatables = false
    @State private var includeBlowers = false

    @State private var swiftastic = false
    @State private var wwdcParty = true
    @State private var offTheCharts = true
    @State private var oneMoreThing = false

    @State private var selectedDecorations: [Decoration] = []
    @State private var decorationThemes: [Decoration: Theme] = [
        .balloon : .blue,
        .confetti: .gold,
        .inflatables: .black,
        .noisemakers: .white,
        .none: .black
    ]

    private var themes: [Binding<Theme>] {
        if selectedDecorations.count == 0 {
            return [Binding($decorationThemes[.none])!]
        }
        return selectedDecorations.compactMap {
            Binding($decorationThemes[$0])
        }
    }

    var body: some View {
        Form {
            Section {
                LabeledContent("Location") {
                    AddressView(location)
                }
                DatePicker("Date", selection: $date)
                TextField("Description", text: $eventDescription, axis: .vertical)
                    .lineLimit(3, reservesSpace: true)
            }

            Section("Vibe") {
                Picker("Accent color", selection: $accent) {
                    ForEach(Theme.allCases) { accent in
                        Text(accent.rawValue.capitalized).tag(accent)
                    }
                }
                Picker("Color scheme", selection: $scheme) {
                    Text("Light").tag(ColorScheme.light)
                    Text("Dark").tag(ColorScheme.dark)
                }
                #if os(macOS)
                .pickerStyle(.inline)
                #endif
                Toggle(isOn: $extraGuests) {
                    Text("Allow extra guests")
                    Text("The more the merrier!")
                }
                if extraGuests {
                    Stepper("Guests limit", value: $spacesCount, format: .number)
                }
            }

            Section("Decorations") {
                Section {
                    List {
                        DisclosureGroup {
                            HStack {
                                Toggle("Balloons 🎈", isOn: $includeBalloons)
                                Spacer()
                                decorationThemes[.balloon].map { $0.swatch }
                            }
                            .tag(Decoration.balloon)

                            HStack {
                                Toggle("Confetti 🎊", isOn: $includeConfetti)
                                Spacer()
                                decorationThemes[.confetti].map { $0.swatch }
                            }
                            .tag(Decoration.confetti)

                            HStack {
                                Toggle("Inflatables 🪅", isOn: $includeInflatables)
                                Spacer()
                                decorationThemes[.inflatables].map { $0.swatch }
                            }
                            .tag(Decoration.inflatables)

                            HStack {
                                Toggle("Party Horns 🥳", isOn: $includeBlowers)
                                Spacer()
                                decorationThemes[.noisemakers].map { $0.swatch }
                            }
                            .tag(Decoration.noisemakers)
                        } label: {
                            Toggle("All Decorations", isOn: [
                                $includeBalloons, $includeConfetti,
                                $includeInflatables, $includeBlowers
                            ])
                            .tag(Decoration.all)
                        }
                        #if os(macOS)
                        .toggleStyle(.checkbox)
                        #endif
                    }

                    Picker("Decoration theme", selection: themes) {
                        Text("Blue").tag(Theme.blue)
                        Text("Black").tag(Theme.black)
                        Text("Gold").tag(Theme.gold)
                        Text("White").tag(Theme.white)
                    }
                    #if os(macOS)
                    .pickerStyle(.radioGroup)
                    #endif
                }
            }

            Section("Hashtags") {
                VStack(alignment: .leading) {
                    HStack {
                        Toggle("#Swiftastic", isOn: $swiftastic)
                        Toggle("#WWParty", isOn: $wwdcParty)
                    }
                    HStack {
                        Toggle("#OffTheCharts", isOn: $offTheCharts)
                        Toggle("#OneMoreThing", isOn: $oneMoreThing)
                    }
                }
                .toggleStyle(.button)
                .buttonStyle(.bordered)
            }

        }
        .formStyle(.grouped)
    }
}

struct AddressView: View {
    private let location: Location

    init(_ location: Location) {
        self.location = location
    }

    var body: some View {
        VStack {
            Text(location.firstLine)
            Text(location.secondLine)
        }
    }
}

struct Location {
    let firstLine: String
    let secondLine: String
}

19:33 - Accessibility Quick Actions

struct ContentView: View {
    @State private var isInCart: Bool = false

    var body: some View {
        VStack(alignment: .leading) {
            ItemDescriptionView()
            addToCartButton
        }
        .accessibilityQuickAction(style: .prompt) {
            addToCartButton
        }
    }

    var addToCartButton: some View {
        Button(isInCart ? "Remove from cart" : "Add to cart") {
            isInCart.toggle()
        }
    }
}

struct ItemDescriptionView: View {
    var body: some View {
        ScrollView {
            VStack {
                HStack {
                    Text("🎈")
                        .font(.title2)
                    Text("Balloons")
                        .font(.title3)
                    Spacer()
                }
                .padding(.bottom, 4)
                Text(
                    """
                    This is perhaps our funniest product! It is made up of a
                    rubber fabric and comes in various unique colors.
                    """)
                .font(.caption)
            }
        }
    }
}

20:20 - Tables on iPadOS

struct ContentView: View {
    @StateObject private var attendeeStore = AttendeeStore()
    var body: some View {
        NavigationStack {
            Table(attendeeStore.attendees) {
                TableColumn("Name") { attendee in
                    AttendeeRow(attendee)
                }
                TableColumn("City", value: \.city)
                TableColumn("Status") { attendee in
                    StatusRow(attendee)
                }
            }
            .navigationTitle("Invitations")
            .toolbar(id: "toolbar") {
                ToolbarItem(id: "new", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("New Invitation", systemImage: "envelope")
                    }
                }
                ToolbarItem(id: "edit", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Edit", systemImage: "pencil.circle")
                    }
                }
                ToolbarItem(id: "share", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Share", systemImage: "square.and.arrow.up")
                    }
                }
                ToolbarItem(id: "tag", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Tags", systemImage: "tag")
                    }
                }
                ToolbarItem(
                    id: "reminder", placement: .secondaryAction, showsByDefault: false
                ) {
                    Button(action: {}) {
                        Label("Set reminder", systemImage: "bell")
                    }
                }
            }
            .toolbarRole(.editor)
        }
    }
}

class AttendeeStore: ObservableObject {
    @Published var attendees: [Attendee] = [/* Default attendees */]
}


struct Attendee: Identifiable, Hashable {
    enum Status: String {
        case accepted, declined, maybe

        func displayText() -> Text {
            switch self {
            case .accepted: return Text(
                "Accepted \(Image(systemName: "person.crop.circle.badge.checkmark"))")
            case .maybe: return Text(
                "Maybe \(Image(systemName: "person.crop.circle.badge.questionmark"))")
            case .declined: return Text(
                "Declined \(Image(systemName: "person.crop.circle.badge.minus"))")
            }
        }
    }
    
    let id = UUID()
    let memojiName: String
    let name: String
    let city: String
    let status: Status

    init(memojiName: String, name: String, cities: String, status: Status) {
        self.memojiName = memojiName
        self.name = name
        self.city = cities
        self.status = status
    }
}

struct AttendeeRow: View {
    let attendee: Attendee

    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        HStack {
            Image(attendee.memojiName)
                .resizable()
                .aspectRatio(contentMode: .fill)
                #if os(macOS)
                .frame(width: 20, height: 20)
                .overlay {
                    Circle()
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #else
                .frame(width: 32, height: 32)
                .overlay {
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #endif
            Text(attendee.name)
        }
    }
}

struct StatusRow: View {
    let attendee: Attendee
    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        attendee.status.displayText()
            .symbolVariant(.fill)
            .symbolRenderingMode(.multicolor)
    }
}

21:12 - Context Menu

struct ContentView: View {
    @StateObject private var attendeeStore = AttendeeStore()
    @State private var selection = Set<Attendee.ID>()

    var body: some View {
        NavigationStack {
            Table(attendeeStore.attendees, selection: $selection) {
                TableColumn("Name") { attendee in
                    AttendeeRow(attendee)
                }
                TableColumn("City", value: \.city)
                TableColumn("Status") { attendee in
                    StatusRow(attendee)
                }
            }
            .navigationTitle("Invitations")
            #if os(macOS)
            .contextMenu(forSelectionType: Attendee.ID.self) { selection in
                if selection.isEmpty {
                    Button("New Invitation") { addInvitation() }
                } else if selection.count == 1 {
                    Button("Mark as VIP") { markVIPs(selection) }
                } else {
                    Button("Mark as VIPs") { markVIPs(selection) }
                }
            }
            #endif
            .toolbar(id: "toolbar") {
                ToolbarItem(id: "new", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("New Invitation", systemImage: "envelope")
                    }
                }
                ToolbarItem(id: "edit", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Edit", systemImage: "pencil.circle")
                    }
                }
                ToolbarItem(id: "share", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Share", systemImage: "square.and.arrow.up")
                    }
                }
                ToolbarItem(id: "tag", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Tags", systemImage: "tag")
                    }
                }
                ToolbarItem(
                    id: "reminder", placement: .secondaryAction, showsByDefault: false
                ) {
                    Button(action: {}) {
                        Label("Set reminder", systemImage: "bell")
                    }
                }
            }
            .toolbarRole(.editor)
        }
    }

    private func addInvitation() {}

    private func markVIPs(_ items: Set<String>) {}
}


class AttendeeStore: ObservableObject {
    @Published var attendees: [Attendee] = [/* Default attendees */]
}


struct Attendee: Identifiable, Hashable {
    enum Status: String {
        case accepted, declined, maybe

        func displayText() -> Text {
            switch self {
            case .accepted: return Text(
                "Accepted \(Image(systemName: "person.crop.circle.badge.checkmark"))")
            case .maybe: return Text(
                "Maybe \(Image(systemName: "person.crop.circle.badge.questionmark"))")
            case .declined: return Text(
                "Declined \(Image(systemName: "person.crop.circle.badge.minus"))")
            }
        }
    }

    let id = UUID()
    let memojiName: String
    let name: String
    let city: String
    let status: Status

    init(memojiName: String, name: String, cities: String, status: Status) {
        self.memojiName = memojiName
        self.name = name
        self.city = cities
        self.status = status
    }
}

struct AttendeeRow: View {
    let attendee: Attendee

    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        HStack {
            Image(attendee.memojiName)
                .resizable()
                .aspectRatio(contentMode: .fill)
                #if os(macOS)
                .frame(width: 20, height: 20)
                .overlay {
                    Circle()
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #else
                .frame(width: 32, height: 32)
                .overlay {
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #endif
            Text(attendee.name)
        }
    }
}

struct StatusRow: View {
    let attendee: Attendee
    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        attendee.status.displayText()
            .symbolVariant(.fill)
            .symbolRenderingMode(.multicolor)
    }
}

22:12 - Customizable toolbars

struct ContentView: View {
    @StateObject private var attendeeStore = AttendeeStore()
    @State private var selection = Set<Attendee.ID>()

    var body: some View {
        NavigationStack {
            Table(attendeeStore.attendees, selection: $selection) {
                TableColumn("Name") { attendee in
                    AttendeeRow(attendee)
                }
                TableColumn("City", value: \.city)
                TableColumn("Status") { attendee in
                    StatusRow(attendee)
                }
            }
            .navigationTitle("Invitations")
            #if os(macOS)
            .contextMenu(forSelectionType: Attendee.ID.self) { selection in
                if selection.isEmpty {
                    Button("New Invitation") { addInvitation() }
                } else if selection.count == 1 {
                    Button("Mark as VIP") { markVIPs(selection) }
                } else {
                    Button("Mark as VIPs") { markVIPs(selection) }
                }
            }
            #endif
            .toolbar(id: "toolbar") {
                ToolbarItem(id: "new", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("New Invitation", systemImage: "envelope")
                    }
                }
                ToolbarItem(id: "edit", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Edit", systemImage: "pencil.circle")
                    }
                }
                ToolbarItem(id: "share", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Share", systemImage: "square.and.arrow.up")
                    }
                }
                ToolbarItem(id: "tag", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Tags", systemImage: "tag")
                    }
                }
                ToolbarItem(
                    id: "reminder", placement: .secondaryAction, showsByDefault: false
                ) {
                    Button(action: {}) {
                        Label("Set reminder", systemImage: "bell")
                    }
                }
            }
            .toolbarRole(.editor)
        }
    }

    private func addInvitation() {}

    private func markVIPs(_ items: Set<String>) {}
}


class AttendeeStore: ObservableObject {
    @Published var attendees: [Attendee] = [/* Default attendees */]
}


struct Attendee: Identifiable, Hashable {
    enum Status: String {
        case accepted, declined, maybe

        func displayText() -> Text {
            switch self {
            case .accepted: return Text(
                "Accepted \(Image(systemName: "person.crop.circle.badge.checkmark"))")
            case .maybe: return Text(
                "Maybe \(Image(systemName: "person.crop.circle.badge.questionmark"))")
            case .declined: return Text(
                "Declined \(Image(systemName: "person.crop.circle.badge.minus"))")
            }
        }
    }

    let id = UUID()
    let memojiName: String
    let name: String
    let city: String
    let status: Status

    init(memojiName: String, name: String, cities: String, status: Status) {
        self.memojiName = memojiName
        self.name = name
        self.city = cities
        self.status = status
    }
}

struct AttendeeRow: View {
    let attendee: Attendee

    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        HStack {
            Image(attendee.memojiName)
                .resizable()
                .aspectRatio(contentMode: .fill)
                #if os(macOS)
                .frame(width: 20, height: 20)
                .overlay {
                    Circle()
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #else
                .frame(width: 32, height: 32)
                .overlay {
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #endif
            Text(attendee.name)
        }
    }
}

struct StatusRow: View {
    let attendee: Attendee
    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        attendee.status.displayText()
            .symbolVariant(.fill)
            .symbolRenderingMode(.multicolor)
    }
}

23:17 - Search Tokens

struct ContentView: View {
    public struct AttendeeToken: Identifiable, Equatable, Hashable {
        enum Guts {
            case name
            case location
            case status
        }

        let guts: Guts
        var query: String = .init()

        var id: String {
            self.systemImage
        }

        static let allCases: [AttendeeToken] = [.name, .location, .status]

        mutating func displayName(_ query: String) -> String {
            self.query = query
            switch guts {
            case .name: return "Name contains: \(query)"
            case .location: return "City contains: \(query)"
            case .status: return "Status contains: \(query)"
            }
        }

        var systemImage: String {
            switch guts {
            case .name: return "person"
            case .location: return "location.square"
            case .status: return "person.crop.circle.badge"
            }
        }

        static let name: AttendeeToken = .init(guts: .name)
        static let location: AttendeeToken = .init(guts: .location)
        static let status: AttendeeToken = .init(guts: .status)
    }

    @StateObject private var attendeeStore = AttendeeStore()
    @State private var selection = Set<Attendee.ID>()

    @State private var tokens: [AttendeeToken] = .init()
    @State private var query: String = .init()

    var body: some View {
        NavigationStack {
            Table(attendeeStore.attendees, selection: $selection) {
                TableColumn("Name") { attendee in
                    AttendeeRow(attendee)
                }
                TableColumn("City", value: \.city)
                TableColumn("Status") { attendee in
                    StatusRow(attendee)
                }
            }
            .navigationTitle("Invitations")
            #if os(macOS)
            .contextMenu(forSelectionType: Attendee.ID.self) { selection in
                if selection.isEmpty {
                    Button("New Invitation") { addInvitation() }
                } else if selection.count == 1 {
                    Button("Mark as VIP") { markVIPs(selection) }
                } else {
                    Button("Mark as VIPs") { markVIPs(selection) }
                }
            }
            #endif
            .searchable(text: $query, tokens: $tokens) { token in
                Label(token.query, systemImage: token.systemImage)
            } suggestions: {
                suggestions
            }
            .toolbar(id: "toolbar") {
                ToolbarItem(id: "new", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("New Invitation", systemImage: "envelope")
                    }
                }
                ToolbarItem(id: "edit", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Edit", systemImage: "pencil.circle")
                    }
                }
                ToolbarItem(id: "share", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Share", systemImage: "square.and.arrow.up")
                    }
                }
                ToolbarItem(id: "tag", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Tags", systemImage: "tag")
                    }
                }
                ToolbarItem(
                    id: "reminder", placement: .secondaryAction, showsByDefault: false
                ) {
                    Button(action: {}) {
                        Label("Set reminder", systemImage: "bell")
                    }
                }
            }
            .toolbarRole(.editor)
        }
    }

    @ViewBuilder
    private var suggestions: some View {
        ForEach(attendeeStore.attendees) {
            Text($0.name)
                .foregroundColor(.black)
        }

        if !query.isEmpty {
            ForEach(AttendeeToken.allCases) { token in
                var _token = token
                Label(_token.displayName(query), systemImage: _token.systemImage)
                    .searchCompletion(_token)
            }
        }
    }

    private func addInvitation() {}

    private func markVIPs(_ items: Set<String>) {}
}

class AttendeeStore: ObservableObject {
    @Published var attendees: [Attendee] = [/* Default attendees */]
}

struct Attendee: Identifiable, Hashable {
    enum Status: String {
        case accepted, declined, maybe

        func displayText() -> Text {
            switch self {
            case .accepted: return Text(
                "Accepted \(Image(systemName: "person.crop.circle.badge.checkmark"))")
            case .maybe: return Text(
                "Maybe \(Image(systemName: "person.crop.circle.badge.questionmark"))")
            case .declined: return Text(
                "Declined \(Image(systemName: "person.crop.circle.badge.minus"))")
            }
        }
    }

    let id = UUID()
    let memojiName: String
    let name: String
    let city: String
    let status: Status

    init(memojiName: String, name: String, cities: String, status: Status) {
        self.memojiName = memojiName
        self.name = name
        self.city = cities
        self.status = status
    }
}

struct AttendeeRow: View {
    let attendee: Attendee

    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        HStack {
            Image(attendee.memojiName)
                .resizable()
                .aspectRatio(contentMode: .fill)
                #if os(macOS)
                .frame(width: 20, height: 20)
                .overlay {
                    Circle()
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #else
                .frame(width: 32, height: 32)
                .overlay {
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #endif
            Text(attendee.name)
        }
    }
}

struct StatusRow: View {
    let attendee: Attendee
    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        attendee.status.displayText()
            .symbolVariant(.fill)
            .symbolRenderingMode(.multicolor)
    }
}

23:28 - Search scopes

struct ContentView: View {
    enum AttendanceScope {
        case inPerson
        case online
    }

    public struct AttendeeToken: Identifiable, Equatable, Hashable {
        enum Guts {
            case name
            case location
            case status
        }

        let guts: Guts
        var query: String = .init()

        var id: String {
            self.systemImage
        }

        static let allCases: [AttendeeToken] = [.name, .location, .status]

        mutating func displayName(_ query: String) -> String {
            self.query = query
            switch guts {
            case .name: return "Name contains: \(query)"
            case .location: return "City contains: \(query)"
            case .status: return "Status contains: \(query)"
            }
        }

        var systemImage: String {
            switch guts {
            case .name: return "person"
            case .location: return "location.square"
            case .status: return "person.crop.circle.badge"
            }
        }

        static let name: AttendeeToken = .init(guts: .name)
        static let location: AttendeeToken = .init(guts: .location)
        static let status: AttendeeToken = .init(guts: .status)
    }

    @StateObject private var attendeeStore = AttendeeStore()
    @State private var selection = Set<Attendee.ID>()

    @State private var tokens: [AttendeeToken] = .init()
    @State private var query: String = .init()
    @State private var scope: AttendanceScope = .inPerson

    var body: some View {
        NavigationStack {
            Table(attendeeStore.attendees, selection: $selection) {
                TableColumn("Name") { attendee in
                    AttendeeRow(attendee)
                }
                TableColumn("City", value: \.city)
                TableColumn("Status") { attendee in
                    StatusRow(attendee)
                }
            }
            .navigationTitle("Invitations")
            #if os(macOS)
            .contextMenu(forSelectionType: Attendee.ID.self) { selection in
                if selection.isEmpty {
                    Button("New Invitation") { addInvitation() }
                } else if selection.count == 1 {
                    Button("Mark as VIP") { markVIPs(selection) }
                } else {
                    Button("Mark as VIPs") { markVIPs(selection) }
                }
            }
            #endif
            .searchable(
                text: $query, tokens: $tokens, scope: $scope
            ) { token in
                Label(
                    token.query,
                    systemImage: token.systemImage)
            } scopes: {
                Text("In Person").tag(AttendanceScope.inPerson)
                Text("Online").tag(AttendanceScope.online)
            } suggestions: {
                suggestions
            }
            .toolbar(id: "toolbar") {
                ToolbarItem(id: "new", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("New Invitation", systemImage: "envelope")
                    }
                }
                ToolbarItem(id: "edit", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Edit", systemImage: "pencil.circle")
                    }
                }
                ToolbarItem(id: "share", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Share", systemImage: "square.and.arrow.up")
                    }
                }
                ToolbarItem(id: "tag", placement: .secondaryAction) {
                    Button(action: {}) {
                        Label("Tags", systemImage: "tag")
                    }
                }
                ToolbarItem(
                    id: "reminder", placement: .secondaryAction, showsByDefault: false
                ) {
                    Button(action: {}) {
                        Label("Set reminder", systemImage: "bell")
                    }
                }
            }
            .toolbarRole(.editor)
        }
    }

    @ViewBuilder
    private var suggestions: some View {
        ForEach(attendeeStore.attendees) {
            Text($0.name)
                .foregroundColor(.black)
        }

        if !query.isEmpty {
            ForEach(AttendeeToken.allCases) { token in
                var _token = token
                Label(_token.displayName(query), systemImage: _token.systemImage)
                    .searchCompletion(_token)
            }
        }
    }

    private func addInvitation() {}

    private func markVIPs(_ items: Set<String>) {}
}

class AttendeeStore: ObservableObject {
    @Published var attendees: [Attendee] = [/* Default attendees */]
}


struct Attendee: Identifiable, Hashable {
    enum Status: String {
        case accepted, declined, maybe

        func displayText() -> Text {
            switch self {
            case .accepted: return Text(
                "Accepted \(Image(systemName: "person.crop.circle.badge.checkmark"))")
            case .maybe: return Text(
                "Maybe \(Image(systemName: "person.crop.circle.badge.questionmark"))")
            case .declined: return Text(
                "Declined \(Image(systemName: "person.crop.circle.badge.minus"))")
            }
        }
    }

    let id = UUID()
    let memojiName: String
    let name: String
    let city: String
    let status: Status

    init(memojiName: String, name: String, cities: String, status: Status) {
        self.memojiName = memojiName
        self.name = name
        self.city = cities
        self.status = status
    }
}

struct AttendeeRow: View {
    let attendee: Attendee

    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        HStack {
            Image(attendee.memojiName)
                .resizable()
                .aspectRatio(contentMode: .fill)
                #if os(macOS)
                .frame(width: 20, height: 20)
                .overlay {
                    Circle()
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #else
                .frame(width: 32, height: 32)
                .overlay {
                    RoundedRectangle(cornerRadius: 6)
                        .stroke(Color.gray.opacity(0.2), lineWidth: 1)
                }
                #endif
            Text(attendee.name)
        }
    }
}

struct StatusRow: View {
    let attendee: Attendee
    init(_ attendee: Attendee) {
        self.attendee = attendee
    }

    var body: some View {
        attendee.status.displayText()
            .symbolVariant(.fill)
            .symbolRenderingMode(.multicolor)
    }
}

24:45 - PhotosPicker

import PhotosUI
import CoreTransferable

struct ContentView: View {
    @ObservedObject var viewModel: FilterModel = .shared
    
    var body: some View {
        NavigationStack {
            Gallery()
                .navigationTitle("Birthday Filter")
                .toolbar {
                    PhotosPicker(
                        selection: $viewModel.imageSelection,
                        matching: .images
                    ) {
                        Label("Pick a photo", systemImage: "plus.app")
                    }
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                }
        }
    }
}

struct Gallery: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        VStack {
            switch viewModel.imageState {
            case .success(let image):
                image
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .draggable(image)
            case .loading:
                ProgressView()
            case .empty:
                Text("No Photo \(Image(systemName: "photo"))")
                    .font(.title2)
                    .fontWeight(.semibold)
                Text("Drag and drop a photo or press\n \(Image(systemName: "plus.app")) to choose a photo manually.")
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
            case .failure:
                Image(systemName: "exclamationmark.triangle.fill")
                    .font(.system(size: 40))
                    .foregroundColor(.white)
            }
        }
        .padding()
    }
}

@MainActor
class FilterModel: ObservableObject {
    static let shared = FilterModel()

    enum ImageState {
        case empty, loading(Progress), success(Image), failure(Error)
    }

    @Published private(set) var processedImage: Image?
    @Published var imageState: ImageState = .empty
    @Published var imageSelection: PhotosPickerItem? = nil {
        didSet {
            if let imageSelection = imageSelection {
                let progress = loadTransferable(from: imageSelection)
                imageState = .loading(progress)
            } else {
                imageState = .empty
            }
        }
    }

    func applyFilter() { /* Apply your filter */ }

    private func loadTransferable(from imageSelection: PhotosPickerItem) -> Progress {
        return imageSelection.loadTransferable(type: Image.self) { result in
            DispatchQueue.main.async {
                guard imageSelection == self.imageSelection else { return }
                switch result {
                case .success(let image?):
                    self.imageState = .success(image)
                case .success(nil):
                    self.imageState = .empty
                case .failure(let error):
                    self.imageState = .failure(error)
                }
            }
        }
    }
}

25:51 - ShareLink

import PhotosUI
import CoreTransferable

struct ContentView: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        NavigationStack {
            Gallery()
                .navigationTitle("Birthday Filter")
                .toolbar {
                    PhotosPicker(
                        selection: $viewModel.imageSelection,
                        matching: .images
                    ) {
                        Label("Pick a photo", systemImage: "plus.app")
                    }
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                    if let item = viewModel.processedImage {
                        ShareLink(
                            item: item, preview: SharePreview("Birthday Effects"))
                    }
                }
        }
    }
}

struct Gallery: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        VStack {
            switch viewModel.imageState {
            case .success(let image):
                image
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .draggable(image)
            case .loading:
                ProgressView()
            case .empty:
                Text("No Photo \(Image(systemName: "photo"))")
                    .font(.title2)
                    .fontWeight(.semibold)
                Text("Drag and drop a photo or press\n \(Image(systemName: "plus.app")) to choose a photo manually.")
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
            case .failure:
                Image(systemName: "exclamationmark.triangle.fill")
                    .font(.system(size: 40))
                    .foregroundColor(.white)
            }
        }
        .padding()
    }
}

@MainActor
class FilterModel: ObservableObject {
    static let shared = FilterModel()

    enum ImageState {
        case empty, loading(Progress), success(Image), failure(Error)
    }

    @Published private(set) var processedImage: Image?
    @Published var imageState: ImageState = .empty
    @Published var imageSelection: PhotosPickerItem? = nil {
        didSet {
            if let imageSelection = imageSelection {
                let progress = loadTransferable(from: imageSelection)
                imageState = .loading(progress)
            } else {
                imageState = .empty
            }
        }
    }

    func applyFilter() { /* Apply your filter */}

    private func loadTransferable(from imageSelection: PhotosPickerItem) -> Progress {
        return imageSelection.loadTransferable(type: Image.self) { result in
            DispatchQueue.main.async {
                guard imageSelection == self.imageSelection else { return }
                switch result {
                case .success(let image?):
                    self.imageState = .success(image)
                case .success(nil):
                    self.imageState = .empty
                case .failure(let error):
                    self.imageState = .failure(error)
                }
            }
        }
    }
}

26:17 - Context Menu

import PhotosUI
import CoreTransferable

struct ContentView: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        NavigationStack {
            Gallery()
                .navigationTitle("Birthday Filter")
                .toolbar {
                    PhotosPicker(
                        selection: $viewModel.imageSelection,
                        matching: .images
                    ) {
                        Label("Pick a photo", systemImage: "plus.app")
                    }
                    if let item = viewModel.processedImage {
                        ShareLink(
                            item: item, preview: SharePreview("Birthday Effects"))
                    }
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                }
                .contextMenu {
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                    if let item = viewModel.processedImage {
                        ShareLink(
                            item: item, preview: SharePreview("Birthday Effects"))
                    }
                    Button(role: .destructive) {
                        viewModel.deleteCurrentPhoto()
                    } label: {
                        Label("Delete", systemImage: "trash")
                    }
                }
        }
    }
}

struct Gallery: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        VStack {
            switch viewModel.imageState {
            case .success(let image):
                image
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .draggable(image)
            case .loading:
                ProgressView()
            case .empty:
                Text("No Photo \(Image(systemName: "photo"))")
                    .font(.title2)
                    .fontWeight(.semibold)
                Text("Drag and drop a photo or press\n \(Image(systemName: "plus.app")) to choose a photo manually.")
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
            case .failure:
                Image(systemName: "exclamationmark.triangle.fill")
                    .font(.system(size: 40))
                    .foregroundColor(.white)
            }
        }
        .padding()
    }
}

@MainActor
class FilterModel: ObservableObject {
    static let shared = FilterModel()

    enum ImageState {
        case empty, loading(Progress), success(Image), failure(Error)
    }

    @Published private(set) var processedImage: Image?
    @Published var imageState: ImageState = .empty
    @Published var imageSelection: PhotosPickerItem? = nil {
        didSet {
            if let imageSelection = imageSelection {
                let progress = loadTransferable(from: imageSelection)
                imageState = .loading(progress)
            } else {
                imageState = .empty
            }
        }
    }

    func applyFilter() { /* Apply your filter */}

    func deleteCurrentPhoto() {}

    private func loadTransferable(from imageSelection: PhotosPickerItem) -> Progress {
        return imageSelection.loadTransferable(type: Image.self) { result in
            DispatchQueue.main.async {
                guard imageSelection == self.imageSelection else { return }
                switch result {
                case .success(let image?):
                    self.imageState = .success(image)
                case .success(nil):
                    self.imageState = .empty
                case .failure(let error):
                    self.imageState = .failure(error)
                }
            }
        }
    }
}

26:50 - Drop destination

import PhotosUI
import CoreTransferable

struct ContentView: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        NavigationStack {
            Gallery()
                .navigationTitle("Birthday Filter")
                .toolbar {
                    PhotosPicker(
                        selection: $viewModel.imageSelection,
                        matching: .images
                    ) {
                        Label("Pick a photo", systemImage: "plus.app")
                    }
                    if let item = viewModel.processedImage {
                        ShareLink(
                            item: item, preview: SharePreview("Birthday Effects"))
                    }
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                }
                .contextMenu {
                    Button {
                        viewModel.applyFilter()
                    } label: {
                        Label("Apply Filter", systemImage: "camera.filters")
                    }
                    if let item = viewModel.processedImage {
                        ShareLink(
                            item: item, preview: SharePreview("Birthday Effects"))
                    }
                    Button(role: .destructive) {
                        viewModel.deleteCurrentPhoto()
                    } label: {
                        Label("Delete", systemImage: "trash")
                    }
                }
                .dropDestination(payloadType: Image.self) { receivedImages, location in
                    guard let image = receivedImages.first else {
                        return false
                    }
                    viewModel.imageState = .success(image)
                    return true
                }
        }
    }
}

struct Gallery: View {
    @ObservedObject var viewModel: FilterModel = .shared

    var body: some View {
        VStack {
            switch viewModel.imageState {
            case .success(let image):
                image
                    .resizable()
                    .aspectRatio(contentMode: .fill)
                    .draggable(image)
            case .loading:
                ProgressView()
            case .empty:
                Text("No Photo \(Image(systemName: "photo"))")
                    .font(.title2)
                    .fontWeight(.semibold)
                Text("Drag and drop a photo or press\n \(Image(systemName: "plus.app")) to choose a photo manually.")
                    .foregroundColor(.secondary)
                    .multilineTextAlignment(.center)
            case .failure:
                Image(systemName: "exclamationmark.triangle.fill")
                    .font(.system(size: 40))
                    .foregroundColor(.white)
            }
        }
        .padding()
    }
}

@MainActor
class FilterModel: ObservableObject {
    static let shared = FilterModel()

    enum ImageState {
        case empty, loading(Progress), success(Image), failure(Error)
    }

    @Published private(set) var processedImage: Image?
    @Published var imageState: ImageState = .empty
    @Published var imageSelection: PhotosPickerItem? = nil {
        didSet {
            if let imageSelection = imageSelection {
                let progress = loadTransferable(from: imageSelection)
                imageState = .loading(progress)
            } else {
                imageState = .empty
            }
        }
    }

    func applyFilter() { /* Apply your filter */}

    func deleteCurrentPhoto() {}

    private func loadTransferable(from imageSelection: PhotosPickerItem) -> Progress {
        return imageSelection.loadTransferable(type: Image.self) { result in
            DispatchQueue.main.async {
                guard imageSelection == self.imageSelection else { return }
                switch result {
                case .success(let image?):
                    self.imageState = .success(image)
                case .success(nil):
                    self.imageState = .empty
                case .failure(let error):
                    self.imageState = .failure(error)
                }
            }
        }
    }
}

28:15 - Shape Styles: CalendarIcon

struct CalendarIcon: View {
    var body: some View {
        VStack {
            Image(systemName: "calendar")
                .font(.system(size: 80, weight: .medium))
            Text("June 6")
        }
        .background(in: Circle().inset(by: -20))
        .backgroundStyle(
            .blue
            .gradient
        )
        .foregroundStyle(.white.shadow(.drop(radius: 1, y: 1.5)))
        .padding(20)
    }
}

28:49 - Shape Styles: Icon Grid

struct Icon: View {
    let systemSymbolName: String
    let color: Color
    let shadow: ShadowStyle
    var foregroundColor: Color = .white

    var body: some View {
        VStack {
            Image(systemName: systemSymbolName)
                .resizable()
                .aspectRatio(1.0, contentMode: .fit)
                .padding(2)
        }
        .background(in: Circle().inset(by: -20))
        .backgroundStyle(
            color
            .gradient
        )
        .foregroundStyle(foregroundColor.shadow(shadow))
        .padding(20)
    }
}

private let dropStyle = ShadowStyle.drop(radius: 1, y: 1.5)
private let innerStyle = ShadowStyle.inner(radius: 1.5)

let icons: [Icon]  = [
    Icon(systemSymbolName: "person", color: .red, shadow: dropStyle),
    Icon(systemSymbolName: "basketball", color: .orange, shadow: dropStyle),
    Icon(systemSymbolName: "globe.central.south.asia", color: .yellow, shadow: innerStyle),
    Icon(systemSymbolName: "carrot", color: .green, shadow: innerStyle, foregroundColor: .orange),
    Icon(systemSymbolName: "sailboat", color: .mint, shadow: innerStyle),
    Icon(systemSymbolName: "figure.open.water.swim", color: .teal, shadow: dropStyle),
    Icon(systemSymbolName: "ladybug.fill", color: .cyan, shadow: innerStyle),
    Icon(systemSymbolName: "calendar", color: .blue, shadow: dropStyle),
    Icon(systemSymbolName: "moon.stars", color: .indigo, shadow: dropStyle),
    Icon(systemSymbolName: "brain.head.profile", color: .purple, shadow: innerStyle),
    Icon(systemSymbolName: "birthday.cake", color: .pink, shadow: dropStyle),
    Icon(systemSymbolName: "house.circle.fill", color: .white, shadow: dropStyle),
    Icon(systemSymbolName: "lizard", color: .brown, shadow: dropStyle),
    Icon(systemSymbolName: "flag.checkered", color: .black, shadow: dropStyle),
    Icon(systemSymbolName: "character.book.closed", color: .gray, shadow: dropStyle),
]

struct IconGrid: View {
    var body: some View {
        Grid(horizontalSpacing: 16, verticalSpacing: 16) {
            ForEach(0..<3) { i in
                GridRow {
                    ForEach(0..<5) { j in
                        icons[i * 5 + j]
                    }
                }
            }
        }
        .background(.black.opacity(0.8))
    }
}

29:07 - Graphics: Dancing symbol grid

// MARK: - Dancing Symbol Grid

struct SymbolSquare: View {
    let color: Color
    let imageName: String
    var image: some View {
        Image(systemName: imageName)
            .resizable()
            .aspectRatio(contentMode: .fit)
            .padding()
            .frame(maxWidth: .infinity, maxHeight: .infinity)
    }

    var body: some View {
        image
            .background {
                RoundedRectangle(cornerRadius: 6, style: .continuous)
                    .fill(
                        .ellipticalGradient(
                            color
                                .gradient
                        )
                    )
            }
    }
}

/// If `true`, the party will commence. 
private let startTheParty = false

private let partySymbols = ["party.popper", "balloon", "balloon.2", "birthday.cake"]

struct DancingSymbolSquare: View {
    let color: Color
    let imageName: String
  
    /// Allows staggered dancing — doesn't look quite as nice.
    let seed: Int
    private let timer = Timer.publish(every: 0.234378662, on: .main, in: .default)
    @State private var cancellable: Cancellable? = nil
    @State private var heavy = false
    @State var fontSize = 20 as CGFloat

    var body: some View {
        SymbolSquare(color: color, imageName: imageName)
            .font(.body.weight(heavy ? .black : .thin))
            .onReceive(timer) { date in
                if heavy {
                    withAnimation(.easeOut(duration: 0.468757324 - 0.1)) {
                        heavy.toggle()
                    }
                } else {
                    withAnimation(.easeIn(duration: 0.1)) {
                        heavy.toggle()
                    }
                }
            }
            .onAppear {
                if startTheParty {
                    DispatchQueue.main.asyncAfter(deadline: .now()  + Double(seed) * 0.25) {
                        cancellable = timer.connect()
                    }
                }
            }
            .drawingGroup(opaque: true)
    }
}

struct SymbolGrid: View {
    var body: some View {
        Grid {
            GridRow {
                DancingSymbolSquare(color: .yellow, imageName:partySymbols[0], seed: 0)
                DancingSymbolSquare(color: .green, imageName: partySymbols[1], seed: 0)
            }

            GridRow {
                DancingSymbolSquare(color: .indigo, imageName: partySymbols[2], seed: 0)
                DancingSymbolSquare(color: .purple, imageName: partySymbols[3],  seed: 0)
            }
        }
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

30:15 - Graphics: Text transitions

struct TextTransitionsView: View {
    @State private var expandMessage = true
    private let mintWithShadow: AnyShapeStyle = AnyShapeStyle(Color.mint.shadow(.drop(radius: 2)))
    private let primaryWithoutShadow: AnyShapeStyle = AnyShapeStyle(Color.primary.shadow(.drop(radius: 0)))

    var body: some View {
        Text("Happy Birthday SwiftUI!")
            .font(expandMessage ? .largeTitle.weight(.heavy) : .body)
            .foregroundStyle(expandMessage ? mintWithShadow : primaryWithoutShadow)
            .onTapGesture { withAnimation { expandMessage.toggle() }}
            .frame(maxWidth: expandMessage ? 160 : 250)
            .drawingGroup()
            .padding(20)
            .background(.pink.opacity(0.3), in: RoundedRectangle(cornerRadius: 6))
    }
}

31:16 - Layout: Grid

struct VIPDetailView: View {
    var body: some View {
        Grid {
            GridRow {
                NameHeadline()
                    .gridCellColumns(2)
            }
            GridRow {
                CalendarIcon()
                SymbolGrid()
            }
        }
        .frame(width: 300, height: 300)
    }
}

struct NameHeadline: View {
    var body: some View {
        HStack {
            Color.green.background(in: RoundedRectangle(cornerRadius: 8))
                .frame(maxWidth: .infinity, maxHeight: .infinity)
            VStack(alignment: .leading) {
                Text("Franck Ndame Mpouli")
                    .font(.title2)
                    .foregroundStyle(.shadow(.drop(radius: 2, y: 3)))
                Text("Party Planning Committee").bold()
            }
        }
        .padding()
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .background(
            .white.gradient,
            in: RoundedRectangle(cornerRadius: 12, style: .continuous)
        )
    }
}

struct CalendarIcon: View {
    var body: some View {
        VStack {
            Image(systemName: "calendar")
                .font(.system(size: 80, weight: .medium))
            Text("June 6")
        }
        .background(in: Circle().inset(by: -20))
        .backgroundStyle(
            .blue
            .gradient
        )
        .foregroundStyle(.white.shadow(dropStyle))
        .padding(20)
        .frame(maxWidth: .infinity, maxHeight: .infinity)
    }
}

32:04 - Layout: Seating Chart Layout

// MARK: Custom Table Layout

private let tableSize = CGSize(width: 130, height: 90)
private let guestSize = CGSize(width: 40, height: 40)

/// Which of 6 tables this view represents
private struct TableViewLayoutKey: LayoutValueKey {
    static let defaultValue: Int? = nil
}

extension View {
    fileprivate func tableViewLayoutKey(_ value: Int) -> some View  {
        return layoutValue(key: TableViewLayoutKey.self, value: value)
    }
}

/// Which of 36 guests this view represents
private struct GuestViewLayoutKey: LayoutValueKey {
    static let defaultValue: Int? = 0
}

extension View {

    /// Guests 1 - 36
    fileprivate func guestViewLayoutKey(_ value: Int) -> some View  {
        return layoutValue(key: GuestViewLayoutKey.self, value: value)
    }
}

let initials = [
"Ju",
"As",
"Ma",
"As",
"Ly",
"Ga",
"Ni",
"Ar",
"Ca",
"Do",
"Je",
"Ca",
"Em",
"Ma",
"Ze",
"Jo",
"Da",
"Sh",
"Sa",
"Pl",
"Pa",
"Sc",
"Ma",
"Je",
"Li",
"Ma",
"Ta",
"Je",
"Cu",
"Lu",
"Ra",
"Na",
"Sa",
"Pa",
"Le",
"Pi",
]

struct SeatingChartView: View {

    /// If true, the guests will be positioned in "pods" of tables. No table will touch another table. Otherwise
    /// the guests will side in two longs rows.
    @State private var usePods = true

    var body: some View {
        ZStack(alignment: .bottomTrailing) {
            GeometryReader { proxy in
                SeatingLayout(usePods: usePods).callAsFunction {
                    TableView(tableNumber: 1)
                    TableView(tableNumber: 2)
                    TableView(tableNumber: 3)
                    TableView(tableNumber: 4)
                    TableView(tableNumber: 5)
                    TableView(tableNumber: 6)
                    ForEach(1..<37) { i in
                        SeatedGuestOption2(guestNumber: i - 1)
                    }
                }
                .animation(.default, value: proxy.size)
            }
            .background(.black.opacity(0.13))
            Picker("Arrangement", selection: $usePods.animation()) {
                Text("Pods").tag(true)
                Text("Rows  ").tag(false)
            }
            .fixedSize()
            .pickerStyle(.segmented)
            .padding()
        }
    }
}

/// heh.
struct TableView: View {
    let tableNumber: Int

    var body: some View {
        ZStack(alignment: .bottomTrailing) {
            HStack {
                Image(systemName: "table.furniture")
                    .background(.quaternary.shadow(.inner(radius: 1, y: 1.5)),
                                in: Circle().inset(by: -8))
                    .padding(5)
                Text("Table \(tableNumber)")
            }
            .foregroundStyle(.secondary)
            .padding(8)
            .frame(width: tableSize.width, height: tableSize.height)
            #if os(macOS) || os(iOS)
            .background(.regularMaterial.shadow(.drop(radius: 1, y: 1.5)),
                        in: RoundedRectangle(cornerRadius: 12, style: .continuous))
            #endif
        }

        .tableViewLayoutKey(tableNumber)
    }
}

private let colors: [Color] = [
    .red, .orange, .yellow, .green, .mint, .teal, .cyan, .blue,
    .indigo, .purple, .pink, .gray, .black, .white, .brown,
    .red, .orange, .yellow, .green, .mint, .teal, .cyan, .blue,
    .indigo, .purple, .pink, .gray, .black, .white, .brown, .red,
    .orange, .yellow, .green, .mint, .teal, .cyan
]

struct SeatedGuest: View {

    let guestNumber: Int

    var body: some View {
        Image(systemName: "person")
            .resizable()
            .aspectRatio(contentMode: .fit)
            .padding(9)
            .background(in: Circle())
            .backgroundStyle(
                colors[guestNumber].gradient
            )
            .foregroundStyle(guestNumber == 13 ? .black : .white)
            .frame(width: 40, height: 40)
            .guestViewLayoutKey(guestNumber + 1)
    }
}

struct SeatedGuestOption2: View {
    let guestNumber: Int

    var body: some View {
        Circle()
            .stroke(colors[guestNumber], style: StrokeStyle(lineWidth: 3))
            .background(.white.gradient, in: Circle())
            .frame(width: guestSize.width, height: guestSize.height)
            .guestViewLayoutKey(guestNumber + 1)
            .overlay {
                Text(initials[guestNumber])
                    .foregroundColor(.secondary)
                    .font(.callout)

            }
    }
}

struct SeatingChartView_Previews: PreviewProvider {
    static var previews: some View {
        SeatingChartView()
            .frame(width: 600, height: 600)
    }
}

struct SeatingLayout: Layout {

    /// If true, the guests will be positioned in "pods" of tables. No table will touch another table. Otherwise
    /// the guests will side in two longs rows.
    let usePods: Bool

    struct Cache {
        ///  The width proposed to the view. We assume a certain height, otherwise, overlapping views
        var width: CGFloat?
    }

    func sizeThatFits(
        proposal: ProposedViewSize,
        subviews: LayoutSubviews,
        cache: inout Cache
    ) -> CGSize {
        cache.width = proposal.width
        return proposal.replacingUnspecifiedDimensions()
    }

    func makeCache(subviews: Subviews) -> Cache { Cache() }

    func placeSubviews(in bounds: CGRect,
                       proposal: ProposedViewSize,
                       subviews: Subviews,
                       cache: inout Cache) {
        guard let width = cache.width else { return }

        /// Helper function: Place 6 guests around all edges of a table.
        func seat(_ guests: [LayoutSubview], around table: CGRect) {
            guests[0].place(
                at: .init(
                    x: table.origin.x + 3 - guestSize.width,
                    y: table.origin.y + (table.height / 2.0) - (guestSize.height / 2.0)),
                proposal: .infinity)
            guests[1].place(
                at: .init(
                    x: table.origin.x + (table.width / 4.0) - guestSize.width / 2.0,
                    y: table.origin.y + 5 - guestSize.height),
                proposal: .infinity)
            guests[2].place(
                at: .init(
                    x: table.origin.x + table.width * 0.75 - guestSize.width / 2.0,
                    y: table.origin.y + 5 - guestSize.height),
                proposal: .infinity)
            guests[3].place(
                at: .init(
                    x: table.maxX - 5,
                    y: table.origin.y + (table.height / 2.0) - (guestSize.height / 2.0)),
                proposal: .infinity)
            guests[4].place(
                at: .init(
                    x: table.origin.x + table.width * 0.75 - guestSize.width / 2.0,
                    y: table.maxY - 5),
                proposal: .infinity)
            guests[5].place(
                at: .init(
                    x: table.origin.x + (table.width / 4.0) - guestSize.width / 2.0,
                    y: table.maxY - 5),
                proposal: .infinity)
        }

        /// Helper function: Place 6 guests, dining hall style (not along the shorter sides of a table)
        func seat(_ guests: [LayoutSubview], along table: CGRect) {
            guests[0].place(
                at: .init(
                    x: table.minX + tableSize.width / 3 - guestSize.width - 4,
                    y: table.origin.y + 5 - guestSize.height),
                proposal: .infinity)
            guests[1].place(
                at: .init(
                    x: table.minX + tableSize.width * 2/3 - guestSize.width - 4,
                    y: table.origin.y + 5 - guestSize.height),
                proposal: .infinity)
            guests[2].place(
                at: .init(
                    x: table.minX + tableSize.width - guestSize.width - 4,
                    y: table.origin.y + 5 - guestSize.height),
                proposal: .infinity)
            guests[3].place(
                at: .init(
                    x: table.minX + tableSize.width / 3 - guestSize.width - 4,
                    y: table.maxY - 5),
                proposal: .infinity)
            guests[4].place(
                at: .init(
                    x: table.minX + tableSize.width * 2/3 - guestSize.width - 4,
                    y: table.maxY - 5),
                proposal: .infinity)
            guests[5].place(
                at: .init(
                    x: table.minX + tableSize.width - guestSize.width - 4,
                    y: table.maxY - 5),
                proposal: .infinity)
        }

        // Get tables
        let table1 = subviews.first(where: { $0[TableViewLayoutKey.self] == 1 })!
        let table2 = subviews.first(where: { $0[TableViewLayoutKey.self] == 2 })!
        let table3 = subviews.first(where: { $0[TableViewLayoutKey.self] == 3 })!
        let table4 = subviews.first(where: { $0[TableViewLayoutKey.self] == 4 })!
        let table5 = subviews.first(where: { $0[TableViewLayoutKey.self] == 5 })!
        let table6 = subviews.first(where: { $0[TableViewLayoutKey.self] == 6 })!

        // Get guests
        let table1Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 1 && guestNumber <= 6
            }
        let table2Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 7 && guestNumber <= 12
            }
        let table3Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 13 && guestNumber <= 18
            }
        let table4Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 19 && guestNumber <= 24
            }
        let table5Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 25 && guestNumber <= 30
            }
        let table6Guests = subviews
            .filter {
                guard let guestNumber = $0[GuestViewLayoutKey.self] else { return false }
                return guestNumber >= 31 && guestNumber <= 36
            }

        if usePods {
            let table1Origin = CGPoint(x: 60, y: 120)
            let table2Origin = CGPoint(x: 200, y: 280)
            let table3Origin = CGPoint(x: 50, y: 450)
            let table4Origin = CGPoint(x: 300, y: 120)
            let table5Origin = CGPoint(x: 440, y: 280)
            let table6Origin = CGPoint(x: 290, y: 450)
            table1.place(at: table1Origin, proposal: .infinity)
            table2.place(at: table2Origin, proposal: .infinity)
            table3.place(at: table3Origin, proposal: .infinity)
            table4.place(at: table4Origin, proposal: .infinity)
            table5.place(at: table5Origin, proposal: .infinity)
            table6.place(at: table6Origin, proposal: .infinity)
            seat(table1Guests, around: CGRect(origin: table1Origin, size: tableSize))
            seat(table2Guests, around: CGRect(origin: table2Origin , size: tableSize))
            seat(table3Guests, around: CGRect(origin: table3Origin, size: tableSize))
            seat(table4Guests, around: CGRect(origin: table4Origin, size: tableSize))
            seat(table5Guests, around: CGRect(origin: table5Origin , size: tableSize))
            seat(table6Guests, around: CGRect(origin: table6Origin, size: tableSize))
        } else {
            let table1Origin = CGPoint(x: width / 2.0 - 6 - tableSize.width * 1.5, y: 130)
            let table2Origin = CGPoint(x: table1Origin.x + tableSize.width + 6, y: 130)
            let table3Origin = CGPoint(x: table2Origin.x + tableSize.width + 6, y: 130)
            let table4Origin = CGPoint(x: width / 2.0 - 6 - tableSize.width * 1.5, y: 360)
            let table5Origin = CGPoint(x: table1Origin.x + tableSize.width + 6, y: 360)
            let table6Origin = CGPoint(x: table2Origin.x + tableSize.width + 6, y: 360)
            table1.place(at: table1Origin, proposal: .infinity)
            table2.place(at: table2Origin, proposal: .infinity)
            table3.place(at: table3Origin, proposal: .infinity)
            table4.place(at: table4Origin, proposal: .infinity)
            table5.place(at: table5Origin, proposal: .infinity)
            table6.place(at: table6Origin, proposal: .infinity)
            seat(table1Guests, along: CGRect(origin: table1Origin, size: tableSize))
            seat(table2Guests, along: CGRect(origin: table2Origin , size: tableSize))
            seat(table3Guests, along: CGRect(origin: table3Origin, size: tableSize))
            seat(table4Guests, along: CGRect(origin: table4Origin, size: tableSize))
            seat(table5Guests, along: CGRect(origin: table5Origin , size: tableSize))
            seat(table6Guests, along: CGRect(origin: table6Origin, size: tableSize))
        }
    }
}

32:50 - AnyLayout invitation

import SwiftUI
import GameplayKit
import Combine

@main
struct InvitationApp: App {
    var body: some Scene {
        WindowGroup {
            PolygonDesignerView()
                .environmentObject(PolygonModel())
            #if os(iOS)
                .statusBar(hidden: true)
            #endif
                .edgesIgnoringSafeArea(.all)
        }
    }
}

// MARK: Views

/// A view that arranges polygons in a grid, or a custom, scattered layout.
private struct DynamicPolygonView: View {
    @EnvironmentObject var model: PolygonModel
    @Binding var cycleLayouts: Bool

    private var sideLength: Int {
        Int(CGFloat(model.polygonGeometries.count).squareRoot())
    }

    /// Timer whose ticking dictates how often to regenerate and animate-to a new scattered layout.
    /// - Note: The layout will only transition if `cycleLayouts` is `true`.
    private let layoutChangingTimer = Timer
        .publish(every: 1.2, on: .current, in: .default).autoconnect()

    /// Animation used to transition layouts
    private let animation = Animation.easeInOut(duration: 1.3)

    /// Timer that ticks at 128 beats per minute, matching the beat of the song in the WWDC session.
    let musicBeatTimer = Timer
        .publish(every: 0.234378662, tolerance: 0,  on: .main, in: .default)

    @State private var musicBeatTimerCancellable: (any Cancellable)? = nil

    /// Whether or not the font should be rendered heavy.
    @State private var heavy: Bool = false

    @State private var scatteredLayout = newScatteredLayout(
        Date(timeIntervalSince1970: 0)
    )

    /// By providing a seed value, the `ScatteredLayout` struct will know when to bust its cache and
    /// generate new layout data.
    private static func newScatteredLayout(_ seed: Date) -> ScatteredLayout {
        ScatteredLayout(count: PolygonModel.total,
                        seed: seed.timeIntervalSinceReferenceDate,
                        textAvoidanceRect: CGRect(
                            x: 152,
                            y: 245,
                            width: 220,
                            height: 40)
        )
    }

    var body: some View {
        let layout = model.usesGridLayout
        ? AnyLayout(Grid(alignment: .center,
                         horizontalSpacing: 0,
                         verticalSpacing: 0))
        : AnyLayout(scatteredLayout)

        ZStack(alignment: .center) {
            Label(title:  {
                Text("You're Invited")
            }, icon: { Image(systemName: "party.popper.fill")})
            .font(.system(size:100).weight(heavy ? .black : .thin))
            .onTapGesture {
                musicBeatTimerCancellable = musicBeatTimer.connect()
            }
            .zIndex(-1)

            layout {
                ForEach((0..<sideLength), id: \.self) { row in
                    GridRow { // GridRow is a no-op in non-Grid layouts
                        ForEach((0..<sideLength), id: \.self) { column in
                            let polygon = model
                                .polygonGeometries[sideLength * row + column]
                            PolygonView(polygonGeometry: polygon)
                                .polygonViewLayoutKey(polygon)
                        }
                    }
                }
            }
        }
        .drawingGroup()
        .frame(maxWidth: .infinity, maxHeight: .infinity)
        .onReceive(musicBeatTimer) { date in
            if heavy {
                // Transitioning to a thin font happens slowly
                withAnimation(.easeOut(duration: 0.468757324 - 0.1)) {
                    heavy.toggle()
                }
            } else {
                // Transitioning to thick happens quickly, to give the
                // appearance of a "strong" downbeat
                withAnimation(.easeIn(duration: 0.1)) {
                    heavy.toggle()
                }
            }
        }
        .onReceive(layoutChangingTimer) { date in
            guard cycleLayouts else { return }
            withAnimation(animation) {
                scatteredLayout = DynamicPolygonView.newScatteredLayout(date)
            }

        }
    }
}

private struct PolygonDesignerView: View {
    @EnvironmentObject var model: PolygonModel
    @State var cycleLayouts = false
    @State var hideDesignerView = true

    var body: some View {
        ZStack(alignment: .bottom) {
            DynamicPolygonView(cycleLayouts: $cycleLayouts)
                .onTapGesture(count: 2) {
                    withAnimation {
                        hideDesignerView.toggle()
                    }
                }
            ControlView(cycleLayouts: $cycleLayouts)
                .padding()
                .background(.thickMaterial)
                .offset(CGSize(width: 0, height: hideDesignerView ? 300 : 0))
        }
    }
}

/// Tunes the parameters of a `PolygonModel`
private struct ControlView: View {

    /// The instance `self` tunes the parameters of.
    @EnvironmentObject var model: PolygonModel

    /// Can be used by a parent view to cycle through instances of layouts.
    @Binding var cycleLayouts: Bool

    var body: some View {
        VStack {
            Button("Reset", action: model.reset)
            let layout = HStack()
            layout {
                Toggle("Tiled", isOn: Binding(get: {
                    model.tiled
                }, set: { tile in
                    // After toggled, wait 5 seconds, then transition back to a
                    // scattered layout
                    DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
                        withAnimation(.linear(duration: 1.4)) {
                            model.usesGridLayout = false
                            model.drawAsRandomPolygons = true
                        }
                    }

                    withAnimation(.linear(duration: 1.8)) {
                        model.usesGridLayout = tile
                        model.drawAsRandomPolygons = !tile
                    }
                }))

                Toggle("Cycle Layouts", isOn: $cycleLayouts)
            }
        }
        .padding(2)
    }
}

// MARK: PolygonView

/// Wraps a ``Polygon`` shape applying a fill.
private struct PolygonView: View {
    var polygonGeometry: PolygonGeometry

    var body: some View {
        Polygon(polygonGeometry: polygonGeometry)
            .fill(polygonGeometry.color)
    }
}

/// A Polygon shape that supports any number of sides as defined by `polygonGeometry`
private struct Polygon: Shape {
    var polygonGeometry: PolygonGeometry

    typealias AnimatableData = AnimatableVector

    var animatableData: AnimatableVector {
        get { polygonGeometry.vectorPath }
        set { polygonGeometry.points = newValue.points }
    }

    func path(in rect: CGRect) -> Path {
        // Scale up the shape's path to fill as much space as it is given
        let path = polygonGeometry.path
        let boundingRect = path.boundingRect

        let xScale = rect.width / boundingRect.width
        let yScale = rect.height / boundingRect.height

        let translate = CGAffineTransform(
            translationX: -boundingRect.origin.x * xScale,
            y: -boundingRect.origin.y * yScale
        )
        let scale = CGAffineTransform(scaleX: xScale, y: yScale)
        return path.applying(scale.concatenating(translate))
    }

    func sizeThatFits(_ proposal: ProposedViewSize) -> CGSize {
        if proposal == .infinity {
            // If proposed infinite space, use the preferred, absolute size.
            return CGSize(width: polygonGeometry.sideLength,
                          height: polygonGeometry.sideLength)
        } else {
            // If we don't have infinite space, assume we've been given all the
            // space the parent view can afford, and take all of it.
            return proposal.replacingUnspecifiedDimensions()
        }
    }
}

// MARK: ScatteredLayout

private struct PolygonViewLayoutKey: LayoutValueKey {
    static let defaultValue: PolygonGeometry? = nil
}

extension View {
    fileprivate func polygonViewLayoutKey(_ value: PolygonGeometry)
    -> some View {
        return layoutValue(key: PolygonViewLayoutKey.self, value: value)
    }
}

/// ScatteredLayout assumes a certain standard size and lays out its views
/// (tagged with `PolygonViewLayoutKey` data) such that they don't collide
/// within that size. As the size grows, the shapes stay the same size,
/// but get farther or closer.
private struct ScatteredLayout: Layout {

    /// Cache data for a `ScatteredLayout`.
    struct Cache {

        /// Maps a `PolygonGeometry.id` to its position in a `standardSize`
        /// coordinate space.
        var rects: [UUID: CGRect]

        /// Used as a cache buster.
        var seed: TimeInterval?
    }

    /// The smallest size a view using this layout can be.
    private let minimumBaseSize: CGSize

    /// The base coordinate system this view assumes when laying out.
    private let standardSize: CGSize = CGSize(width: 500, height: 500)

    /// Clients can pass a value here and polygons won't be placed in that rect.
    var textAvoidanceRect: CGRect = .zero

    /// If different, we've been requested to bust the cache, and create a new
    /// one.
    /// - Note the cache can persist across different instances of a
    ///  `ScatteredLayout`
    private let seed: TimeInterval

    func sizeThatFits(
        proposal: ProposedViewSize,
        subviews: LayoutSubviews,
        cache: inout Cache
    ) -> CGSize {
        let proposedSize = proposal
            .replacingUnspecifiedDimensions(by: minimumBaseSize)
        return CGSize(
            width: proposedSize.width
                .clamped(
                    to: minimumBaseSize.width..<CGFloat.greatestFiniteMagnitude
                ),
            height: proposedSize.height
                .clamped(
                    to: minimumBaseSize.height..<CGFloat.greatestFiniteMagnitude
                )
        )
    }

    init(count: Int, seed: TimeInterval, textAvoidanceRect: CGRect = .zero) {
        self.seed = seed
        minimumBaseSize = CGSize(width: CGFloat(count), height: CGFloat(count))
        self.textAvoidanceRect = textAvoidanceRect
    }

    func makeCache(subviews: Subviews) -> Cache {
        var cache: Cache =  Cache(rects: [:], seed: self.seed)
        var placedPolygons: [CGRect] = []

        for subview in subviews {

            guard let polygon = subview[PolygonViewLayoutKey.self] else {
                // This is the title text view, skip it.
                continue
            }

            var subviewsPreferredSize = subview.sizeThatFits(.infinity)
            var counter = 20

            while counter > 0 {
                counter -= 1
                let randomX = CGFloat.random(in: 0..<standardSize.width)
                let randomY: CGFloat
                if randomX > textAvoidanceRect.minX
                    && randomX < textAvoidanceRect.maxX {
                    // Pick from either above or below the avoidance rect
                    if Bool.random() {
                        randomY = CGFloat.random(
                            in: 0..<textAvoidanceRect.minY
                        )
                    } else {
                        randomY = CGFloat.random(
                            in: textAvoidanceRect.maxY..<standardSize.height
                        )
                    }
                } else {
                    randomY = CGFloat.random(in: 0..<standardSize.height)
                }

                let origin = CGPoint(x: randomX, y: randomY)
                let rect = CGRect(origin: origin, size: subviewsPreferredSize)

                if placedPolygons.allSatisfy({ placed in
                    !placed.intersects(rect)
                }) && !rect.intersects(textAvoidanceRect) {
                    // The shape found a non-overlapping place to be. Lock in
                    // it's position
                    placedPolygons.append(rect)
                    cache.rects[polygon.id] =
                    CGRect(origin: origin,
                           size: subviewsPreferredSize)
                    break
                } else  {
                    if (counter == 0) {
                        if rect.intersects(textAvoidanceRect) {
                            subviewsPreferredSize = .zero
                        }
                        placedPolygons.append(rect)
                        cache.rects[polygon.id] =
                        CGRect(origin: origin,
                               size: subviewsPreferredSize)
                    }
                }
            }
        }
        return cache
    }

    func placeSubviews(in bounds: CGRect,
                       proposal: ProposedViewSize,
                       subviews: Subviews,
                       cache: inout Cache) {
        // We have the frame value cached (via makeCache())
        // for every view to be placed in a `standardSize` coordinate system.
        // Now we need to map that `standardSize` to the size was proposed.
        let proposedSize = proposal
            .replacingUnspecifiedDimensions(by: minimumBaseSize)
        let xProposedToBaseRatio = proposedSize.width / standardSize.width
        let yProposedToBaseRatio = proposedSize.height / standardSize.height

        for subview in subviews {
            guard let uuid = subview[PolygonViewLayoutKey.self]?.id, let rect =
                    cache.rects[uuid] else {
                let desiredSize = subview.sizeThatFits(.zero)
                let centered = desiredSize.centered(in: bounds)
                subview.place(
                    at: centered.origin,
                    proposal: ProposedViewSize(
                        width: desiredSize.width,
                        height: desiredSize.height
                    )
                )
                continue
            }

            let mappedPoint = CGPoint(x: rect.origin.x * xProposedToBaseRatio,
                                      y: rect.origin.y * yProposedToBaseRatio)

            subview.place(at: mappedPoint,
                          proposal: ProposedViewSize(width: rect.size.width,
                                                     height:rect.size.height)
            )
        }
    }

    func updateCache(_ cache: inout Cache, subviews: Subviews) {

        // Bust the cache if we've been given a new seed value
        // or if our subviews have been swapped out from underneath us.
        if self.seed != cache.seed
            || !cache.rects.contains(where: { (key: UUID, value: CGRect) in
                subviews.first?[PolygonViewLayoutKey.self]?.id == key
            })  {
            cache = makeCache(subviews: subviews)
            return
        }
    }

}

/// This struct facilitates animation of point-based `Path`s so long as said
/// source and destination `Path` have an equal number of vertices.
private struct AnimatableVector: VectorArithmetic {

    static var zero: AnimatableVector = AnimatableVector(points: [])

    private(set) var points: [CGPoint]

    var magnitudeSquared: Double {
        let squared = points.map { point in
            CGPoint(x: point.x * point.x, y: point.y * point.y)
        }
        let sumOfSquares = squared.map { point in // dot product?
            sqrt(point.x + point.y)
        }
        let sum = sumOfSquares.reduce(0, +)
        return Double(sum)
    }

    /// Facilitates a valid `.zero` value, no matter the dimension of the vector
    subscript(safe index: Int) -> CGPoint {
        return (self.points.count <= index) ? .zero : points[index]
    }

    static func - (lhs: AnimatableVector, rhs: AnimatableVector)
    -> AnimatableVector {
        let negated = rhs.points.map { CGPoint(x: -$0.x, y: -$0.y) }
        return lhs + AnimatableVector(points: negated)
    }

    static func + (lhs: AnimatableVector, rhs: AnimatableVector)
    -> AnimatableVector {
        var output: [CGPoint] = []
        for i in 0..<lhs.points.count {
            output.append(CGPoint(x: lhs[safe: i].x + rhs[safe: i].x,
                                  y:lhs[safe: i].y + rhs[safe: i].y ))
        }
        return AnimatableVector(points: output)
    }

    mutating func scale(by rhs: Double) {
        points = points.map { CGPoint(x: $0.x * CGFloat(rhs),
                                      y: $0.y * CGFloat(rhs)) }
    }
}

// MARK: Random Polygon Generation & Geometry

private let mean: Float = 10
private let deviation: Float = 3
private let gaussian = GKGaussianDistribution(
    randomSource: GKARC4RandomSource(),
    mean: mean,
    deviation: deviation)

/// Factory type for creating points describing a random Polygon
private struct PolygonGeometry: Identifiable, Equatable, Hashable {

    /// The horizontal and vertical side lengths of the polygon's bounding box.
    let sideLength: CGFloat

    /// A constant count of the total points that comprise this
    /// `PolygonGeometry`'s path. Clients can set `points` to a new value, but
    /// the new value should have the same `count` for smooth `Path` animations
    let numberOfVertices: Int

    /// Supports animation of point-based `Path`s by providing an array of
    /// points that can be interpolated.
    var vectorPath: AnimatableVector {
        AnimatableVector(points: points)
    }

    /// If `false`, this instance will present itself as a rectangular shape
    /// (not necessarily with 4 vertices) that fills available space.
    private(set) var drawsAsPolygon: Bool = true

    /// Points describing the `Path` used to render `self`.
    var points: [CGPoint] {
        willSet {
            assert(points.count == polygonPathPoints.count)
        }
    }

    /// Delineate the path of the random polygon.
    private let polygonPathPoints: [CGPoint]

    let color: Color = [
        Color(red: 0.73, green: 0.20, blue: 0.20),
        Color(red: 0.95, green: 0.66, blue: 0.24),
        Color(red: 0.14, green: 0.29, blue: 0.49),
        Color(red: 0.46, green: 0.76, blue: 0.67),
        Color(red: 0.30, green: 0.33, blue: 0.22),
        Color(red: 0.49, green: 0.55, blue: 0.64),
        Color(red: 0.92, green: 0.53, blue: 0.30),
        Color(red: 0.20, green: 0.45, blue: 0.55),
        Color(red: 0.41, green: 0.45, blue: 0.45),
        Color(red: 0.87, green: 0.67, blue: 0.61)
    ].randomElement()!

    private var spikiness: CGFloat = 0.2
    private var irregularity: CGFloat = 0.2

    let id = UUID()

    /// Owning `Shape` instances should use this to draw.
    var path: Path { Path(from: points) }

    init(pointsVector: [CGPoint], sideLength: CGFloat) {
        self.numberOfVertices = pointsVector.count
        self.points = pointsVector
        self.polygonPathPoints = points
        self.sideLength = sideLength
    }

    func drawn(asRandomizedPolygon: Bool) -> Self {
        var copy = self
        copy.drawsAsPolygon = asRandomizedPolygon
        copy.points = asRandomizedPolygon
        ? copy.polygonPathPoints
        : CGRect(x: 0, y: 0, width: 1, height: 1)
            .pointSequence(of: copy.numberOfVertices)
        return copy
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
    }
}

/// A namespace around functionality to generate a  path drawn in a 1x1 square
/// with configurable "irregularity" and "spikiness".
/// The closer both are to zero, the closer the generated polygon is to a
/// [regular polygon](https://mathworld.wolfram.com/RegularPolygon.html)
private enum UnitPolygonGeometryFactory {

    /// The maximum possible radius. A value of 0.5 restricts the algorithm
    /// to the unit square.
    private static let maxRadius: CGFloat = 0.5

    /// A — by no means definitive — algorithm for creating an arbitrary
    /// polygon of `vertexCount` vertices
    /// - Parameters:
    ///   - vertexCount: How many vertices (and edges) the polygon will have
    ///   - irregularity: A subjective term for how "irregular" the polygon is.
    ///   A fully regular polygon has all equal sides, assuming 0 `spikinesss`.
    ///   - spikiness: A subjective term for how "spiky" the polygon is.
    ///   A polygon with high spikiness will have more vertices closer and
    ///   farther from where the vertex would be on a regular polygon.
    /// - Returns: An array of points representing the point-based path of
    /// the polygon
    static func random(vertexCount: Int,
                       irregularity: CGFloat = 0.2,
                       spikiness: CGFloat = 0.2)
    -> [CGPoint] {

        let floatVertices = CGFloat(vertexCount)

        // Irregularity is how much we're willing to allow the angular steps to
        // vary from "perfect". For example, in a regular (all sides equal)
        // six-sided polygon, each angular step is 2𝜋 / 6. Irregularity
        // defines the range that value can take, centered around a mean of
        // 2𝜋 / 6. We accept an irregularity between 0 and 1, and then
        // scale it for how much that represents out of a circle's radians.
        let scaledIrregularity = irregularity * 2.0 * CGFloat.pi / floatVertices

        // Spikiness describes how often we want to see values that are very
        // far from where a vertex of a regular polygon would be. For example,
        // a high positive spikiness might push a vertex radially very far from
        // the center, leading to a big "spike". Meanwhile, a spikiness of 0
        // will yield more circular polygons.
        let denormalizedSpikiness = spikiness * maxRadius

        let gaussian = GKGaussianDistribution(
            randomSource: GKARC4RandomSource(),
            mean: Float(maxRadius * 1024),
            deviation: Float(denormalizedSpikiness * 1024))

        // Generate the angular steps
        var raidanAngleSteps: [CGFloat] = []

        // Both of these measured in radians
        let minimumSliceWidth =
        (2.0 * CGFloat.pi / floatVertices) - scaledIrregularity
        let maximumSliceWidth =
        (2.0 * CGFloat.pi / floatVertices) + scaledIrregularity

        var sum: CGFloat = 0

        for _ in (0..<vertexCount) {
            let radians = CGFloat
                .random(in: minimumSliceWidth...maximumSliceWidth)
            raidanAngleSteps.append(radians)
            sum += radians
        }

        // Re-divide these steps so the point 0 and n+1 are the same.
        // I.e. if the random angle generation from the above loop yielded
        // more or less than 2𝜋 radians, reapportion those divisions to sum to
        // 2𝜋.
        let k = sum / (2 * CGFloat.pi)
        (0..<vertexCount).forEach { i in
            raidanAngleSteps[i] /= k
        }

        let maximumPossibleGaussianSample = CGFloat(
            gaussian.mean + Float(denormalizedSpikiness * 1024)*3
        )

        // Finally, make all of the normalized points within a 1x1 square
        // Unlike the unit circle of traditional geometry, because (0, 0) is in
        // the top left, (0.5, 0.5) is in the middle. Thus, positively
        // incrementing the angle moves us clockwise around the circle
        var points: [CGPoint] = []
        let center = CGPoint(x: maxRadius, y: maxRadius)
        var cumulativeAngle: CGFloat = 0.0
        for i in (0..<Int(vertexCount)) {

            // * 2 to keep the sample <= 0.5 (`maxRadius)
            let radiusForPoint = CGFloat(gaussian.nextInt())
            / (maximumPossibleGaussianSample * 2)

            let x = center.x + radiusForPoint * cos(cumulativeAngle)
            let y = center.y + radiusForPoint * sin(cumulativeAngle)
            points.append(CGPoint(x: x, y: y))

            cumulativeAngle += raidanAngleSteps[i]
        }
        return points
    }
}

// MARK: Observable Polygon Model

/// A `PolygonModel` describes a collection of randomized ``Polygons`` that
/// can be laid out by `AnyLayout` type.
private class PolygonModel: ObservableObject {

    static let total = (maxSides - minSides + 1) * polygonsPerSideCount

    /// The minimum sides the randomly generated sides will have
    private static let minSides = 4

    /// The maximum sides the randomly generated sides will have
    private static let maxSides = 7

    /// The number of randomly generated polygons to make _per side length_.
    private static let polygonsPerSideCount = 32

    /// All `PolygonGeometry`s that are laid out with `scatteredLayout`
    @Published var polygonGeometries: [PolygonGeometry] = makeGeometries()

    /// If `true`, `self` is expressing a grid layout with rectangular tiles.
    var tiled: Bool { usesGridLayout && !drawAsRandomPolygons }

    /// If `true`, ignore `scatteredLayout` and instead use a `Grid` layout
    @Published var usesGridLayout: Bool = false

    /// If `true`, `polygonGeometries` draw themselves as randomized polygons.
    /// If false, a rectangle that fills all available space.
    @Published var drawAsRandomPolygons: Bool = true {
        didSet {
            polygonGeometries = polygonGeometries.map {
                $0.drawn(asRandomizedPolygon: drawAsRandomPolygons)
            }
        }
    }

    /// Tunable by clients to experiment with different values.
    let spikiness: CGFloat = 0.2
    /// Tunable by clients to experiment with different values.
    let irregularity: CGFloat = 0.2

    /// Creates many ``PolygonGeometry`` instances with the given parameters.
    /// - Parameters:
    ///   - irregularity: A subjective term for how "irregular" the polygon is.
    ///   A fully regular polygon has all equal sides, assuming 0 `spikinesss`.
    ///   - spikiness: A subjective term for how "spiky" the polygon is.
    ///   A polygon with high spikiness will have more vertices closer and
    ///   farther from where the vertex would be on a regular polygon.
    /// - Returns: An array of `n` polygons where `n` is defined by the
    ///  `PolygonModel` class.
    private static func makeGeometries(
        irregularity: CGFloat = 0.3,
        spikiness: CGFloat = 0.3) -> [PolygonGeometry] {
            var scales: Array<CGFloat> = polygonSizeRatios
                .reduce(into: []) { partialResult, sizeRatio in
                    let (size, percentage) = sizeRatio
                    let scalesToMake = Int(ceil(percentage * CGFloat(total)))
                    partialResult.append(contentsOf: (0..<scalesToMake)
                        .map { _ in CGFloat.random(in: size.sizeRange) })
                }.shuffled()

            return (minSides...maxSides).flatMap { vertexCount in
                return (0..<polygonsPerSideCount).map { _ in
                    let unitPolygon = UnitPolygonGeometryFactory
                        .random(vertexCount: vertexCount,
                                irregularity: irregularity,
                                spikiness: spikiness)
                    let polygonGeometry = PolygonGeometry(
                        pointsVector: unitPolygon,
                        sideLength: scales.removeFirst())
                    return polygonGeometry
                }
            }.shuffled()
        }

    /// Complete remove and regenerate all model data.
    func reset() {
        polygonGeometries.removeAll(keepingCapacity: true)
        polygonGeometries = PolygonModel.makeGeometries(
            irregularity: irregularity,
            spikiness: spikiness
        )
    }
}

private extension PolygonModel {

    /// Use a sampling of various sized polygons
    enum PieceSize: Hashable {
        case tiny
        case small
        case medium
        case large

        /// The range for the side length of the bounding rect of a polygon
        var sizeRange: ClosedRange<CGFloat> {
            switch self {
            case .tiny:
                return 16.0...25.0
            case .small:
                return 25.0...40.0
            case .medium:
                return 40.0...50.0
            case .large:
                return 50.0...65.0
            }
        }
    }

    /// This dictionary denotes the ratio of sizes to use.
    /// - warning: Should sum to 100.
    private static let polygonSizeRatios: [PieceSize: CGFloat] =
    [
        .large: 0.15,
        .medium: 0.25,
        .small: 0.25,
        .tiny: 0.35
    ]
}

// MARK: - Utility Extensions

extension FloatingPoint {

    /// - returns an instance of `Self` clamped to the ``ClosedRange``.
    func clamped(to limits: ClosedRange<Self>) -> Self {
        return min(max(self, limits.lowerBound), limits.upperBound)
    }

    /// - returns an instance of `Self` clamped to the ``Range``.
    /// - note the value returned will be less than the provided upper bound, as
    ///  is dictated by ``Range``.
    func clamped(to limits: Range<Self>) -> Self {
        return min(max(self, limits.lowerBound), limits.upperBound.nextDown)
    }
}

extension CGRect {

    /// Creates a rectangular sequence of `vertexCount `points denoting a
    /// rectangular path.
    /// - note This is helpful for animating a `Path` composed of `vertexCount`
    /// points into a ``Rectangle``.
    func pointSequence(of vertexCount: Int) -> [CGPoint] {
        // Start at a random corner. When many Polygons are using this
        // animation at once, if they all start at the same corner, an
        // unnatural uniformity of motion emerges.
        var startingPercent = [0, 0.25, 0.5, 0.75].randomElement()!
        var points: [CGPoint] = []

        let extraPoints = vertexCount - 4
        let (groups, remainder) = extraPoints
            .quotientAndRemainder(dividingBy: 3)

        for edge in 0...3 {
            points.append(pointAlongPerimeter(at: startingPercent))
            for i in (0..<(edge == 3 ? remainder : groups)) {
                points.append(pointAlongPerimeter(
                    at: startingPercent + 0.25
                    / CGFloat(groups + 1) * CGFloat(i)))
            }
            startingPercent += 0.25
            startingPercent.formTruncatingRemainder(dividingBy: 1)
        }
        assert(points.count == vertexCount)
        return points
    }

    /// Returns the ``CGPoint`` that is `percent` along the path of `self`,
    /// with 0% mapping to the top-left corner, progressing clockwise.
    /// E.g. 50% would map to the bottom right corner if and only if `self` is
    ///  a square.
    /// - Parameters:
    ///   - percent: A percentage between `0.0` and `1.0`
    private func pointAlongPerimeter(at percent: CGFloat) -> CGPoint {
        let perimeter = size.width * 2 + size.height * 2

        // Mark the four corners as percentages around the rect. For example,
        /// these values for a square would be 25%, 50%, 75%, 100%
        let topRight = size.width / perimeter
        let bottomRight = topRight + (size.height / perimeter)
        let bottomLeft = bottomRight + (size.width / perimeter)
        let topLeft = 1.0

        switch percent {
        case 0..<topRight:
            return CGPoint(
                x: percent / topRight * size.width,
                y: minY)
        case topRight..<bottomRight:
            return CGPoint(
                x: maxX,
                y: (percent - topRight)
                / (bottomRight - topRight) * size.height)
        case bottomRight..<bottomLeft:
            return CGPoint(
                x: maxX - ((percent - bottomRight) / (bottomLeft - bottomRight)
                           * size.width),
                y: maxY)
        case bottomLeft...topLeft:
            return CGPoint(
                x: minX,
                y: maxY - (percent - bottomLeft) / (topLeft - bottomLeft)
                * size.height
            )
        default:
            preconditionFailure("Invalid percentage requested")
        }
    }
}

/// Returns a new `CGRect` with the same size as `self`, but centered in `other`
/// vertically, and horizontally.
extension CGSize {
    func centered(in other: CGRect) -> CGRect {
        CGRect(x: other.midX - width / 2.0,
               y: other.midY - height / 2.0,
               width: width,
               height: height)
    }
}

extension Path {
    /// Convenience for initializing a `Path` from an array of `CGPoint`s given
    /// the first point element is the `Path`'s first point.
    init(from points: [CGPoint]) {
        self.init()
        self.addLines(points)
        self.closeSubpath()
    }
}