Essential protocols for your every day iOS needs

UIGestureRecognizerProtocols

Swift 2.0 opens a world of opportunity with enhanced Protocols and Protocol Extensions. This library attempts to address some of the most commonly repeated patterns in iOS apps using protocol oriented programming and reduce the need to create deep, complicated subclassing trees.

Too often we find ourselves locked into deep and complicated subclassing trees just to factor out common behavior in our apps. This makes our code inflexible, hard to navigate, and contain too many dependencies. Using protocols for common features allows us to create default behavior that is additive without complicated subclassing.

1. Make sure you have downloaded and installed cocoapods.
2. Add pod 'STP', '~> 0.3.0'to your podfile.
3. Make sure that your podfile includes use_frameworks!
4. pod install
5. import STC and let the magic happen!

1. Drag and drop the files into your project and build the app. Note you will not get bugfixes, updates, and new releases if you do this. If you want custom features, I reccommend forking this repo.

All too often, we find ourselves subclassing views to allow them to be tappable, moveable, rotatable, and more. These protocols allow you to add these features by simply conforming to a protocol, but still give you the flexible to create custom features and animations.

By default, making a view conform to the Movable protocol will attach a UIPanGestureRecognizer and allow the user to tap on the view and drag it around the screen. The default behavior is for the view to only be dragged within its superview. Creating a moveable view is as simple as:

class MyMoveableView : UIView, Moveable {
    init(frame: CGRect) {
        super.init(frame: frame)
        self.makeMoveable()
    }
}

To do an action on start or finish, or use custom logic for movement or animation, implement the appropriate methods in the Moveable protocol.

func didStartMoving()
func didFinishMoving(velocity:CGPoint)
func canMoveToX(x:CGFloat) -> Bool
func canMoveToY(y:CGFloat) -> Bool
func translateCenter(translation:CGPoint, velocity:CGPoint, startPoint:CGPoint, currentPoint:CGPoint) -> CGPoint
func animateToMovedTransform(transform:CGAffineTransform)

By default, making a view conform to the Pinchable protocol will attach a UIPinchGesetureRecognizer and allow the user to pinch and scale a view. Creating a pinchable view is as simple as:

class MyPinchableView : UIView, Pinchable {
    init(frame: CGRect) {
        super.init(frame: frame)
        self.makePinchable()
    }
}

To do an action on start or finish, or create custom transform or animation logic, simply implement the appropriate methods in the Pinchable protocol

func didStartPinching()
func didFinishPinching()
func maximumPinchScale() -> CGFloat
func minimumPinchScale() -> CGFloat
func transformWithScale(scale:CGFloat, lastScale:CGFloat, velocity:CGFloat) -> CGAffineTransform
func animateToPinchedTransform(transform:CGAffineTransform)

By default, making a view conform to the Rotatable protocol will attach a UIRotationGestureRecognizer and allow the user to use two fingers to rotate a view. Creating a rotatable view is as simple as:

class MyRotatableView : UIView, Rotatable {
    init(frame: CGRect) {
        super.init(frame: frame)
        self.makeRotatable()
    }
}

To do an action on start or finish, or create custom transform or animation logic, simply implement the appropriate methods in the Rotatable protocol

func didStartRotating()
func didFinishRotating(velocity:CGFloat)
func minimumRotation() -> CGFloat
func maximumRotation() -> CGFloat
func transformWithRotation(rotation:CGFloat, lastRotation:CGFloat, velocity:CGFloat) -> CGAffineTransform
func animateToRotatedTransform(transform:CGAffineTransform)

By default, making a view conform to the Tappable protocol will attach a UILongPressGestureRecognizer and allow the user to tap. It will call the didTap() method and set the alpha of the view to 0.5 on the down state and 1.0 on the up state. Creating a tappable view is as simple as:

class MyTappableView : UIView, Tappable {
    init(frame: CGRect) {
        super.init(frame: frame)
        self.makeTappable()
    }
    
    func didTap() {
         print("tapped!")
    }
}

To do customize the up and down state and/or adjust the minimum press duration and allowable movement, simply implement the appropriate methods in the Tappable protocol.

func didTap()
func didTouchDown()
func didTouchUp()
func minimumPressDuration() -> NSTimeInterval
func allowableMovement() -> CGFloat

By default, making a view conform to the Forceable protocol will attach a ForceTouchGestureRecognizer and allow the user to press down with a force. It will call the didForce() method, but doesn't have any default behavior. Creating a forceable view is as simple as:

class ForceView: UIView, Forceable {
    override init(frame: CGRect) {
        super.init(frame: frame)
        self.makeForceable()
    }
}

To do customize the vide on force, simply implement the appropriate methods in the Forceable protocol.

func didStartForcing(force:CGFloat)
func didForce(force:CGFloat, lastForce:CGFloat)
func didFinishForcing(force:CGFloat)

Because protocols are addative, you can mix and match these protocols to create even more dynamic views. Creating a view that movable, pinchable, rotatable, and tappable is as easy as:

class MyAwesomeView : UIView, Moveable, Rotatable, Pinchable, Tappable {
    init(frame: CGRect) {
        super.init(frame: frame)
        self.makeMoveable()
        self.makeRotatable()
        self.makePinchable()
        self.makeTappable()
    }
}

Pull requests are welcome! :) You can also email me or contact me on Twitter if you have any questions, ideas, or just want to contribute.

t: @chrisoneil_

e: cconeil5@gmail.com

A special thanks to jhurray for inspring me to do work on some open source code.

There's a ton that we can do here, and I would love to hear suggestions and get pull requets. Here are some things that I'm planning to work on in the immediate future.

1. A protocol for view controllers that implements default peek and pop for force touch.
2. A protocol for view controllers that drops down an error banner.

Standard Template Protocols is released under the MIT license. See LICENSE for details.