你可以改变你的UILabel的大小和字体与动画如下..这里我只是把如何改变UILabel的字体与变换动画的例子。

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);
    }];

2017年以后......

• • 雨燕3.0、4.0**

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

危重：

避免模糊的关键点是必须从最大尺寸开始，然后缩小它。然后在需要时扩展到"1"。

为了快速"弹出"（如高亮动画），可以扩展到1以上，但如果您在两个大小之间转换，* 请将较大的大小设置为"正确"的正常大小 *。

我在Swift中创建了UILabel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，则取消注解行。

也可以使用CATextLayer，它将fontSize作为可设置动画的属性。

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
这个动画保持字体左上对齐（不像CGAffineTransformScale从中心缩放标签），赞成或反对取决于您的需要。CATextLayer的缺点是CALayers不支持自动布局约束动画（我碰巧需要它，并通过创建一个只包含CATextLayer的UIView并对其约束进行动画处理来解决它）。

对于那些不寻求转换，而是寻求实际值变化的人：

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

适用于想要调整动画方向的用户

我已经为UILabel创建了一个扩展来动态显示字体大小的变化

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
    }
  }

如果你想调整动画的方向，使用下面的方法，并把一个合适的锚点。

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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，要将标签字体大小更改为30，持续时间从中心开始为1s，比例更大。

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

目标C

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

斯威夫特3.0和斯威夫特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      

    }

我发现这里的每一条建议都不充分，原因如下：
1.它们实际上并不改变字体大小。
1.他们不玩好帧大小和自动布局。
1.它们的接口并不简单，并且/或者在动画块中不能很好地发挥作用。
为了保留所有这些特性，并且仍然获得平滑的动画过渡，我结合了变换方法和字体方法。
界面很简单，只需要更新fontSize属性，就可以更新字体大小，在动画块中完成这个操作，它就会有动画效果。

@interface UILabel(MPFontSize)

@property(nonatomic) CGFloat fontSize;

@end

至于实现，有简单的方法，也有更好的方法。
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在完成时可能会断断续续，因为视图的框架一直基于原始字体来调整大小，直到动画完成，此时框架会更新以适应没有动画的目标字体。
解决这个问题有点困难，因为我们需要覆盖intrinsicContentSize。你可以通过子类化UILabel或者混合方法来实现。我个人混合了这个方法，因为它让我保持一个通用的fontSize属性对所有UILabel可用，但是这取决于一些库代码，我不能在这里分享。下面是你如何使用子类化来实现这一点。
接口：

@interface AnimatableLabel : UILabel

@property(nonatomic) CGFloat fontSize;

@end

实施：

@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

如果您想从另一个锚点设置文本大小的动画，下面是Swift 5解决方案：

如何申请：

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

分机号：

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)
  }
}