代码：

ViewController：

#import @interface ViewController : UIViewController@end#import "ViewController.h"#import "HWButton.h"#define mainW [UIScreen mainScreen].bounds.size.width#define mainH [UIScreen mainScreen].bounds.size.height@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {  [super viewDidLoad];  self.view.backgroundColor = [UIColor blackColor];  //创建控件  [self creatButton];}- (void)creatButton{  HWButton *button = [[HWButton alloc] initWithFrame:CGRectMake(mainW * 0.5 - 60, mainH - 100, 120, 72) maxLeft:100 maxRight:100 maxHeight:300];  [button setImage:[UIImage imageNamed:@"button"] forState:UIControlStateNormal];  button.images = @[[UIImage imageNamed:@"Circle 1"], [UIImage imageNamed:@"Circle 2"], [UIImage imageNamed:@"Circle 3"], [UIImage imageNamed:@"Hero"]];  button.duration = 10;  [button addTarget:self action:@selector(buttonOnClick:) forControlEvents:UIControlEventTouchUpInside];  [self.view addSubview:button];}- (void)buttonOnClick:(HWButton *)btn{  [btn generateBubbleInRandom];}@end

HWButton：

#import @interface HWButton : UIButton@property (nonatomic, assign) CGFloat maxLeft;@property (nonatomic, assign) CGFloat maxRight;@property (nonatomic, assign) CGFloat maxHeight;@property (nonatomic, assign) CGFloat duration;@property (nonatomic, strong) NSArray *images;- (instancetype)initWithFrame:(CGRect)frame maxLeft:(CGFloat)maxLeft maxRight:(CGFloat)maxRight maxHeight:(CGFloat)maxHeight;- (void)generateBubbleWithImage:(UIImage *)image;- (void)generateBubbleInRandom;@end#import "HWButton.h"@implementation HWButton{  CGPoint _startPoint;  CGFloat _maxWidth;  NSMutableSet *_recyclePool;  NSMutableArray *_array;}- (instancetype)initWithFrame:(CGRect)frame maxLeft:(CGFloat)maxLeft maxRight:(CGFloat)maxRight maxHeight:(CGFloat)maxHeight{  self = [super initWithFrame:frame];  if (self) {    _maxHeight = maxHeight;    _maxLeft  = maxLeft;    _maxRight = maxRight;    [self initData];  }  return self;}- (id)initWithCoder:(NSCoder *)aDecoder{  self = [super initWithCoder:aDecoder];  if (self) {    [self initData];  }  return self;}- (void)initData{  _array = @[].mutableCopy;  _recyclePool = [NSMutableSet set];}- (void)generateBubbleInRandom{  CALayer *layer;  if (_recyclePool.count > 0) {    layer = [_recyclePool anyObject];    [_recyclePool removeObject:layer];  }else {    UIImage *image = self.images[arc4random() % self.images.count];    layer = [self createLayerWithImage:image];  }  [self.layer addSublayer:layer];  [self generateBubbleWithCAlayer:layer];}- (void)generateBubbleWithImage:(UIImage *)image{  CALayer *layer = [self createLayerWithImage:image];  [self.layer addSublayer:layer];  [self generateBubbleWithCAlayer:layer];}- (void)generateBubbleWithCAlayer:(CALayer *)layer{  _maxWidth = _maxLeft + _maxRight + self.bounds.size.width;  _startPoint = CGPointMake(self.frame.size.width / 2, 0);  CGPoint endPoint = CGPointMake(_maxWidth * [self randomFloat] - _maxLeft, -_maxHeight);  CGPoint controlPoint1 = CGPointMake(_maxWidth * [self randomFloat] - _maxLeft, -_maxHeight * 0.2);  CGPoint controlPoint2 = CGPointMake(_maxWidth * [self randomFloat] - _maxLeft, -_maxHeight * 0.6);  CGMutablePathRef curvedPath = CGPathCreateMutable();  CGPathMoveToPoint(curvedPath, NULL, _startPoint.x, _startPoint.y);  CGPathAddCurveToPoint(curvedPath, NULL, controlPoint1.x, controlPoint1.y, controlPoint2.x, controlPoint2.y, endPoint.x, endPoint.y);  CAKeyframeAnimation *keyFrame = [CAKeyframeAnimation animation];  keyFrame.keyPath = @"position";  keyFrame.path = CFAutorelease(curvedPath);  keyFrame.duration = self.duration;  keyFrame.calculationMode = kCAAnimationPaced;  [layer addAnimation:keyFrame forKey:@"keyframe"];  CABasicAnimation *scale = [CABasicAnimation animation];  scale.keyPath = @"transform.scale";  scale.toValue = @1;  scale.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0.1, 0.1, 0.1)];  scale.duration = 0.5;  CABasicAnimation *alpha = [CABasicAnimation animation];  alpha.keyPath = @"opacity";  alpha.fromValue = @1;  alpha.toValue = @0.1;  alpha.duration = self.duration * 0.4;  alpha.beginTime = self.duration - alpha.duration;  CAAnimationGroup *group = [CAAnimationGroup animation];  group.animations = @[keyFrame, scale, alpha];  group.duration = self.duration;  group.delegate = self;  group.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut];  group.fillMode = kCAFillModeForwards;  group.removedOnCompletion = NO;  [layer addAnimation:group forKey:@"group"];  [_array addObject:layer];}- (CGFloat)randomFloat{  return (arc4random() % 100)/100.0f;}- (CALayer *)createLayerWithImage:(UIImage *)image{  CGFloat scale = [UIScreen mainScreen].scale;  CALayer *layer = [CALayer layer];  layer.frame  = CGRectMake(0, 0, image.size.width / scale, image.size.height / scale);  layer.contents = (__bridge id)image.CGImage;;  return layer;}- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{  if (flag) {    CALayer *layer = [_array firstObject];    [layer removeAllAnimations];    [layer removeFromSuperlayer];    [_array removeObject:layer];    [_recyclePool addObject:layer];  }}@end