一看就懂demo下载地址：github
CAReplicatorLayer，负责创建子layer特定数目的copy，这个与别的不太同，别的layer是创建好后添加到父layer，这个则是创建好后添加目标layer为自己的子layer。
1.首先创建一个UIView
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(10, 200, 25, 25)];
view.backgroundColor = [UIColor purpleColor];
view.layer.cornerRadius = CGRectGetHeight(view.bounds)/2;
view.layer.masksToBounds = YES;
view.layer.transform = CATransform3DMakeScale(0.1, 0.1, 0.1);起始大小
2.接着创建一个layer
CAReplicatorLayer *layer = [CAReplicatorLayer layer];
layer.bounds = self.view.bounds;
layer.position = self.view.center;
layer.preservesDepth = YES;
layer.instanceColor = [UIColor whiteColor].CGColor;
layer.instanceCount = 20;copy的数量
layer.instanceDelay = 1.0/20;创建copy的时间间隔
layer.instanceTransform = CATransform3DMakeRotation((2 * M_PI) /20, 0, 0, 1);旋转的角度
[layer addSublayer:view.layer];
[self.view.layer addSublayer:layer];
注意添加顺序，layer添加view的layer作为子layer，self.view再添加layer作为子视图。
3.创建一个动画
CABasicAnimation *ani =
[CABasicAnimation animationWithKeyPath:@"transform.scale"];
animation.duration = 1;
animation.repeatCount = MAXFLOAT;
animation.fromValue = @(1);
animation.toValue = @(0.1);
[view.layer addAnimation:animation forKey:nil];
动画不断重复从大到小的变化，最终效果:
