Adds animated counting support to UILabel.

UICountingLabel is available on CocoaPods. Add this to your Podfile:

pod 'UICountingLabel'

And then run:

$ pod install

Simply initialize a UICountingLabel the same way you set up a regular UILabel:

UICountingLabel* myLabel = [[UICountingLabel alloc] initWithFrame:CGRectMake(10, 10, 100, 40)];
[self.view addSubview:myLabel];

You can also add it to your XIB file, just make sure you set the class type to UICountingLabel instead of UILabel and be sure to #import "UICountingLabel.h" in the header file.

Set the format of your label. This will be filled with a single int or float (depending on how you format it) when it updates:

myLabel.format = @"%d";

Alternatively, you can provide a UICountingLabelFormatBlock, which permits greater control over how the text is formatted:

myLabel.formatBlock = ^NSString* (CGFloat value) {    
    NSInteger years = value / 12;
    NSInteger months = (NSInteger)value % 12;
    if (years == 0) {
        return [NSString stringWithFormat: @"%ld months", (long)months];
    }
    else {
        return [NSString stringWithFormat: @"%ld years, %ld months", (long)years, (long)months];
    }
};

There is also a UICountingLabelAttributedFormatBlock to use an attributed string. If the formatBlock is specified, it takes precedence over the format.

Optionally, set the mode. The default is UILabelCountingMethodEaseInOut, which will start slow, speed up, and then slow down as it reaches the end. Other options are described below in the Methods section.

myLabel.method = UILabelCountingMethodLinear;

When you want the label to start counting, just call:

[myLabel countFrom:50 to:100];

You can also specify the duration. The default is 2.0 seconds.

[myLabel countFrom:50 to:100 withDuration:5.0f];

Additionally, there is animationDuration property which you can use to override the default animation duration.

myLabel.animationDuration = 1.0;

You can use common convinient methods for counting, such as:

[myLabel countFromCurrentValueTo:100];
[myLabel countFromZeroTo:100];

Behind the scenes, these convinient methods use one base method, which has the following full signature:

[myLabel     countFrom:(float)startValue
                    to:(float)endValue
          withDuration:(NSTimeInterval)duration];

You can get current value of your label using -currentValue method (works correctly in the process of animation too):

CGFloat currentValue = [myLabel currentValue];

Optionally, you can specify a completionBlock to perform an acton when the label has finished counting:

myLabel.completionBlock = ^{
    NSLog(@"finished counting");
};

When you set the format property, the label will look for the presence of %(.*)d or %(.*)i, and if found, will cast the value to int before formatting the string. Otherwise, it will format it using a float.

If you're using a float value, it's recommended to limit the number of digits with a format string, such as @"%.1f" for one decimal place.

Because it uses the standard stringWithFormat: method, you can also include arbitrary text in your format, such as @"Points: %i".

There are currently four modes of counting.

Counts linearly from the start to the end.

Ease In starts out slow and speeds up counting as it gets to the end, stopping suddenly at the final value.

Ease Out starts out fast and slows down as it gets to the destination value.

Ease In/Out starts out slow, speeds up towards the middle, and then slows down as it approaches the destination. It is a nice, smooth curve that looks great, and is the default method.

为 UILabel 添加计数动画支持.

UICountingLabel 可以使用cocoaPods导入, 添加以下代码到你的Podfile文件:

pod 'UICountingLabel'

然后运行以下命令:

$ pod install

初始化 UICountingLabel 的方式和普通的 UILabel是一样的:

UICountingLabel* myLabel = [[UICountingLabel alloc] initWithFrame:CGRectMake(10, 10, 100, 40)];
[self.view addSubview:myLabel];

你也可以用在 XIB 文件中, 前提是你在头文件中引入了 UICountingLabel的头文件并且使用 UICountingLabel替换掉了原生的UILabel.

设置标签格式. 设置标签格式后，标签会在更新数值的时候以你设置的方式填充，默认是显示float类型的数值，也可以设置成显示int类型的数值，比如下面的代码:

myLabel.format = @"%d";

另外，你也可以使用 UICountingLabelFormatBlock, 这个可以对显示的文本格式进行更加高度的自定义:

// 举例：把显示的月份数变成几年零几个月的样式
myLabel.formatBlock = ^NSString* (CGFloat value) {    
    NSInteger years = value / 12;
    NSInteger months = (NSInteger)value % 12;
    if (years == 0) {
        return [NSString stringWithFormat: @"%ld months", (long)months];
    }
    else {
        return [NSString stringWithFormat: @"%ld years, %ld months", (long)years, (long)months];
    }
};

除此之外还有一个 UICountingLabelAttributedFormatBlock 用于设置属性字符串的格式,用法和上面的block类似. 如果指定了以上两个 formatBlock中的任意一个 , 它将会覆盖掉 format属性,因为block的优先级更高.

可选项, 设置动画样式. 默认的动画样式是 UILabelCountingMethodEaseInOut, 这个样式是开始时速度比较慢,然后加速,将要结束时减速. 以下将介绍其他动画样式及用法.

myLabel.method = UILabelCountingMethodLinear; // 线性变化

需要计数时只需要使用以下方法即可:

[myLabel countFrom:50 to:100];

可以指定动画的时长，默认时长是2.0秒.

[myLabel countFrom:50 to:100 withDuration:5.0f];

另外也可以使用 animationDuration 属性去设置动画时长.

myLabel.animationDuration = 1.0;

可以使用便利方法计数，例如:

[myLabel countFromCurrentValueTo:100];
[myLabel countFromZeroTo:100];

本质上,这些便利方法都是基于一个总方法封装的, 以下就是这个方法完整的声明:

[myLabel     countFrom:(float)startValue
                    to:(float)endValue
          withDuration:(NSTimeInterval)duration];

可以使用 -currentValue 方法获得当前数据, (即使在动画过程中也可以正常获得):

CGFloat currentValue = [myLabel currentValue];

可以使用 completionBlock 获得动画结束的事件:

myLabel.completionBlock = ^{
    NSLog(@"finished counting");
};

当设置format属性后, 标签会检测是否有%(.*)d或者%(.*)i格式, 如果能找到, 就会将内容以int类型展示. 否则, 将会使用默认的float类型展示.

假如你需要以float类型展示, 最好设置小数点位数限制, 例如使用@"%.1f"来限制只显示一位小数.

因为使用了标准的stringWithFormat:方法, 可以按照自己的意愿自定义格式,例如:@"Points: %i".

当前有四种技术动画样式.

匀速计数动画.

开始比较缓慢,快结束时加速,结束时突然停止.

开始速度很快,快结束时变得缓慢.

开始时比较缓慢，中间加速，快结束时减速.动画速度是一个平滑的曲线,是默认采用的动画样式。