我目前正在制作一个使用自定义View Controller容器的应用程序。一次在屏幕上显示多个视图，而当一个视图被点击时，选定的视图控制器会设置为全屏动画。这样做时，选定的视图控制器子视图也会缩放（帧，字体大小等）。尽管如此，UILabel的font属性无法设置动画，从而导致问题。我已经尝试了多种解决方案，但全部失败了。

我尝试过的解决方案是：

1. 截取较大视图的屏幕截图并为更改添加动画效果（类似于Flipboard的操作）
2. 通过使用transform属性进行动画处理
3. 缩小UIScrollView并在全屏显示时将其放大。
4. 设置将adjustsFontSizeToFitWidth设置为YES，并在动画之前设置fontSize

到目前为止，这是最好的解决方案，但我对此并不满意。

我正在寻找其他建议，如果有人可以使用[UIView animate ..]平滑制作动画或使用UILabel替换动画。

这是一个很好的示例，类似于我希望UILabel进行的操作：http : //www.cocoawithlove.com/2010/09/zoomingviewcontroller-to-animate-uiview.html

编辑：此代码有效

// Load View

self.label = [[UILabel alloc] init];
self.label.text = @"TEXT";
self.label.font = [UIFont boldSystemFontOfSize:20.0];
self.label.backgroundColor = [UIColor clearColor];

[self.label sizeToFit];

[self.view addSubview:self.label];

// Animation

self.label.font = [UIFont boldSystemFontOfSize:80.0];
self.label.transform = CGAffineTransformScale(self.label.transform, .25, .25);
[self.label sizeToFit];

[UIView animateWithDuration:1.0 animations:^{
    self.label.transform = CGAffineTransformScale(self.label.transform, 4.0, 4.0);
    self.label.center = self.view.center;
} completion:^(BOOL finished) {

    self.label.font = [UIFont boldSystemFontOfSize:80.0]; 
    self.label.transform = CGAffineTransformScale(self.label.transform, 1.0, 1.0);

    [self.label sizeToFit];

}];

您可以UILabel使用以下动画来更改动画的大小和字体，例如波纹管..在这里，我仅举一个如何UILabel使用transform Animation ..更改字体的示例。

    yourLabel.font = [UIFont boldSystemFontOfSize:35]; // set font size which you want instead of 35
    yourLabel.transform = CGAffineTransformScale(yourLabel.transform, 0.35, 0.35); 
    [UIView animateWithDuration:1.0 animations:^{
        yourLabel.transform = CGAffineTransformScale(yourLabel.transform, 5, 5);
    }];

希望对您有帮助。

从2017年开始...

雨燕3.0，4.0

UIView.animate(withDuration: 0.5) {
     label.transform = CGAffineTransform(scaleX: 1.1, y: 1.1) //Scale label area
 }

危急：

避免模​​糊的关键点是必须从最大尺寸开始，然后缩小尺寸。然后在需要时扩展为“ 1”。

对于快速的“弹出”（如高亮动画），可以扩展到1以上，但是如果要在两种尺寸之间切换，请将较大的尺寸设为“正确”的正常尺寸。

我已经UILabel在Swift中创建了扩展。

import UIKit

extension UILabel {
    func animate(font: UIFont, duration: TimeInterval) {
        // let oldFrame = frame
        let labelScale = self.font.pointSize / font.pointSize
        self.font = font
        let oldTransform = transform
        transform = transform.scaledBy(x: labelScale, y: labelScale)
        // let newOrigin = frame.origin
        // frame.origin = oldFrame.origin // only for left aligned text
        // frame.origin = CGPoint(x: oldFrame.origin.x + oldFrame.width - frame.width, y: oldFrame.origin.y) // only for right aligned text
        setNeedsUpdateConstraints()
        UIView.animate(withDuration: duration) {
            //L self.frame.origin = newOrigin
            self.transform = oldTransform
            self.layoutIfNeeded()
        }
    }
}

如果标签文本左对齐或右对齐，请取消注释行。

您也可以使用具有fontSize作为动画属性的CATextLayer。

let startFontSize: CGFloat = 20
let endFontSize: CGFloat = 80

let textLayer = CATextLayer()
textLayer.string = "yourText"
textLayer.font = yourLabel.font.fontName as CFTypeRef?
textLayer.fontSize = startFontSize
textLayer.foregroundColor = UIColor.black.cgColor
textLayer.contentsScale = UIScreen.main.scale //for some reason CATextLayer by default only works for 1x screen resolution and needs this line to work properly on 2x, 3x, etc. ...
textLayer.frame = parentView.bounds
parentView.layer.addSublayer(textLayer)

//animation:
let duration: TimeInterval = 1
textLayer.fontSize = endFontSize //because upon completion of the animation CABasicAnimation resets the animated CALayer to its original state (as opposed to changing its properties to the end state of the animation), setting fontSize to endFontSize right BEFORE the animation starts ensures the fontSize doesn't jump back right after the animation.
let fontSizeAnimation = CABasicAnimation(keyPath: "fontSize")
fontSizeAnimation.fromValue = startFontSize
fontSizeAnimation.toValue = endFontSize
fontSizeAnimation.duration = duration
fontSizeAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
textLayer.add(fontSizeAnimation, forKey: nil)

我在我的项目中使用了它：https : //github.com/yinanq/AngelListJobs

该动画使字体保持左上对齐（不像CGAffineTransformScale从中心缩放标签），根据您的需要赞成或反对。CATextLayer的一个缺点是CALayers无法与自动布局约束动画一起使用（我碰巧需要并通过制作仅包含CATextLayer的UIView并对其约束进行动画处理来解决该问题）。

对于想要调整动画方向的人

我创建了一个扩展UILabel来动画字体大小变化

extension UILabel {
  func animate(fontSize: CGFloat, duration: TimeInterval) {
    let startTransform = transform
    let oldFrame = frame
    var newFrame = oldFrame
    let scaleRatio = fontSize / font.pointSize

    newFrame.size.width *= scaleRatio
    newFrame.size.height *= scaleRatio
    newFrame.origin.x = oldFrame.origin.x - (newFrame.size.width - oldFrame.size.width) * 0.5
    newFrame.origin.y = oldFrame.origin.y - (newFrame.size.height - oldFrame.size.height) * 0.5
    frame = newFrame

    font = font.withSize(fontSize)

    transform = CGAffineTransform.init(scaleX: 1 / scaleRatio, y: 1 / scaleRatio);
    layoutIfNeeded()

    UIView.animate(withDuration: duration, animations: {
      self.transform = startTransform
      newFrame = self.frame
    }) { (Bool) in
      self.frame = newFrame
    }
  }

如果要调整动画方向，请使用以下方法并放置合适的锚点。

迅速

struct LabelAnimateAnchorPoint {
  // You can add more suitable archon point for your needs
  static let leadingCenterY         = CGPoint.init(x: 0, y: 0.5)
  static let trailingCenterY        = CGPoint.init(x: 1, y: 0.5)
  static let centerXCenterY         = CGPoint.init(x: 0.5, y: 0.5)
  static let leadingTop             = CGPoint.init(x: 0, y: 0)
}

extension UILabel {
  func animate(fontSize: CGFloat, duration: TimeInterval, animateAnchorPoint: CGPoint) {
    let startTransform = transform
    let oldFrame = frame
    var newFrame = oldFrame
    let archorPoint = layer.anchorPoint
    let scaleRatio = fontSize / font.pointSize

    layer.anchorPoint = animateAnchorPoint

    newFrame.size.width *= scaleRatio
    newFrame.size.height *= scaleRatio
    newFrame.origin.x = oldFrame.origin.x - (newFrame.size.width - oldFrame.size.width) * animateAnchorPoint.x
    newFrame.origin.y = oldFrame.origin.y - (newFrame.size.height - oldFrame.size.height) * animateAnchorPoint.y
    frame = newFrame

    font = font.withSize(fontSize)

    transform = CGAffineTransform.init(scaleX: 1 / scaleRatio, y: 1 / scaleRatio);
    layoutIfNeeded()

    UIView.animate(withDuration: duration, animations: {
      self.transform = startTransform
      newFrame = self.frame
    }) { (Bool) in
      self.layer.anchorPoint = archorPoint
      self.frame = newFrame
    }
  }
}

目标-C

// You can add more suitable archon point for your needs
#define kLeadingCenterYAnchorPoint         CGPointMake(0.f, .5f)
#define kTrailingCenterYAnchorPoint        CGPointMake(1.f, .5f)
#define kCenterXCenterYAnchorPoint         CGPointMake(.5f, .5f)
#define kLeadingTopAnchorPoint             CGPointMake(0.f, 0.f)

@implementation UILabel (FontSizeAnimating)

- (void)animateWithFontSize:(CGFloat)fontSize duration:(NSTimeInterval)duration animateAnchorPoint:(CGPoint)animateAnchorPoint {
  CGAffineTransform startTransform = self.transform;
  CGRect oldFrame = self.frame;
  __block CGRect newFrame = oldFrame;
  CGPoint archorPoint = self.layer.anchorPoint;
  CGFloat scaleRatio = fontSize / self.font.pointSize;

  self.layer.anchorPoint = animateAnchorPoint;

  newFrame.size.width *= scaleRatio;
  newFrame.size.height *= scaleRatio;
  newFrame.origin.x = oldFrame.origin.x - (newFrame.size.width - oldFrame.size.width) * animateAnchorPoint.x;
  newFrame.origin.y = oldFrame.origin.y - (newFrame.size.height - oldFrame.size.height) * animateAnchorPoint.y;
  self.frame = newFrame;

  self.font = [self.font fontWithSize:fontSize];
  self.transform = CGAffineTransformScale(self.transform, 1.f / scaleRatio, 1.f / scaleRatio);
  [self layoutIfNeeded];

  [UIView animateWithDuration:duration animations:^{
    self.transform = startTransform;
    newFrame = self.frame;
  } completion:^(BOOL finished) {
    self.layer.anchorPoint = archorPoint;
    self.frame = newFrame;
  }];
}

@end

例如，要动画化将标签字体大小更改为30，则持续时间应从中心开始1s，并缩放更大。只需致电

迅速

YOUR_LABEL.animate(fontSize: 30, duration: 1, animateAnchorPoint: LabelAnimateAnchorPoint.centerXCenterY)

目标-C

[YOUR_LABEL animateWithFontSize:30 
                       duration:1 
             animateAnchorPoint:kCenterXCenterYAnchorPoint];

对于那些不希望转换但实际值发生变化的用户：

UIView.transition(with: label, duration: 0.25, options: .transitionCrossDissolve, animations: {
    self.label.font = UIFont.systemFont(ofSize: 15)
}) { isFinished in }

Swift 3.0和Swift 4.0

 UIView.animate(withDuration: 0.5, delay: 0.1, options: .curveLinear, animations: { 

    label.transform = label.transform.scaledBy(x:4,y:4) //Change x,y to get your desired effect. 

    } ) { (completed) in

         //Animation Completed      

    }

由于以下原因，我发现这里的每个建议都不足够：

1. 它们实际上并没有更改字体大小。
2. 它们在框架大小调整和自动布局方面效果不佳。
3. 他们的界面很简单，并且/或者在动画块中的播放效果不佳。

为了保留所有这些功能并仍然获得平滑的动画过渡，我将转换方法和字体方法结合在一起。

界面很简单。只需更新fontSize属性，即可更新字体的大小。在动画块中执行此操作，它将进行动画处理。

@interface UILabel(MPFontSize)

@property(nonatomic) CGFloat fontSize;

@end

至于实现，有简单的方法，有更好的方法。

简单：

@implementation UILabel(MPFontSize)

- (void)setFontSize:(CGFloat)fontSize {

    CGAffineTransform originalTransform = self.transform;
    UIFont *targetFont = [self.font fontWithSize:fontSize];

    [UIView animateWithDuration:0 delay:0 options:0 animations:^{
        self.transform = CGAffineTransformScale( originalTransform,
                fontSize / self.fontSize, fontSize / self.fontSize );
    }                completion:^(BOOL finished) {
        self.transform = originalTransform;
        if (finished)
            self.font = targetFont;
    }];
}

- (CGFloat)fontSize {

    return self.font.pointSize;
};

@end

现在，这样做的问题是布局可能在完成时出现断断续续的情况，因为视图的框架始终根据原始字体调整大小，直到动画完成为止，此时框架会更新以适应没有动画的目标字体。

解决这个问题要困难一些，因为我们需要重写intrinsicContentSize。您可以通过子类化UILabel或模糊处理方法来执行此操作。我亲自处理该方法，因为它使我可以将通用fontSize属性保留给所有人使用UILabel，但这取决于一些我在这里无法共享的库代码。这是使用子类进行此操作的方式。

接口：

@interface AnimatableLabel : UILabel

@property(nonatomic) CGFloat fontSize;

@end

实现方式：

@interface AnimatableLabel()

@property(nonatomic) UIFont *targetFont;
@property(nonatomic) UIFont *originalFont;

@end

@implementation AnimatableLabel

- (void)setFontSize:(CGFloat)fontSize {

    CGAffineTransform originalTransform = self.transform;
    self.originalFont = self.font;
    self.targetFont = [self.font fontWithSize:fontSize];
    [self invalidateIntrinsicContentSize];

    [UIView animateWithDuration:0 delay:0 options:0 animations:^{
        self.transform = CGAffineTransformScale( originalTransform,
                fontSize / self.fontSize, fontSize / self.fontSize );
    }                completion:^(BOOL finished) {
        self.transform = originalTransform;

        if (self.targetFont) {
            if (finished)
                self.font = self.targetFont;
            self.targetFont = self.originalFont = nil;
            [self invalidateIntrinsicContentSize];
        }
    }];
}

- (CGFloat)fontSize {

    return self.font.pointSize;
};

- (CGSize)intrinsicContentSize {

    @try {
        if (self.targetFont)
            self.font = self.targetFont;
        return self.intrinsicContentSize;
    }
    @finally {
        if (self.originalFont)
            self.font = self.originalFont;
    }
}

@end

如果要从另一个锚点设置文本大小的动画，请使用Swift 5解决方案：

怎样申请：

yourLabel.setAnimatedFont(.systemFont(ofSize: 48), duration: 0.2, anchorPointX: 0, anchorPointY: 1)

扩充功能：

extension UILabel {
  /// Animate font size from a given anchor point of the label.
  /// - Parameters:
  ///   - duration: Animation measured in seconds
  ///   - anchorPointX: 0 = left, 0.5 = center, 1 = right
  ///   - anchorPointY: 0 = top, 0.5 = center, 1 = bottom
  func setAnimatedFont(_ font: UIFont, duration: TimeInterval, anchorPointX: CGFloat, anchorPointY: CGFloat) {
    guard let oldFont = self.font else { return }

    setAnchorPoint(CGPoint(x: anchorPointX, y: anchorPointY))
    self.font = font

    let scaleFactor = oldFont.pointSize / font.pointSize
    let oldTransform = transform
    transform = transform.scaledBy(x: scaleFactor, y: scaleFactor)
    setNeedsUpdateConstraints()

    UIView.animate(withDuration: duration) {
      self.transform = oldTransform
      self.layoutIfNeeded()
    }
  }
}

extension UIView {
  /// Change the anchor point without moving the view's position.
  /// - Parameters:
  ///   - point: The layer's bounds rectangle.
  func setAnchorPoint(_ point: CGPoint) {
    let oldOrigin = frame.origin
    layer.anchorPoint = point
    let newOrigin = frame.origin

    let translation = CGPoint(x: newOrigin.x - oldOrigin.x, y: newOrigin.y - oldOrigin.y)
    translatesAutoresizingMaskIntoConstraints = true
    center = CGPoint(x: center.x - translation.x, y: center.y - translation.y)
  }
}