CAReplicatorLayer复制Layer和动画, 实现神奇的效果

@interface CAReplicatorLayer : CALayer

@property NSInteger instanceCount;
//复制的个数
@property BOOL preservesDepth;
//这是一个bool值，默认为No，如果设为Yes，将会具有3维透视效果
@property CFTimeInterval instanceDelay;
//复制后的layer相比原来的距离
@property CATransform3D instanceTransform;
//复制layer的坐标系/方向偏转 
@property(nullable) CGColorRef instanceColor;

@property float instanceRedOffset;
@property float instanceGreenOffset;
@property float instanceBlueOffset;
@property float instanceAlphaOffset;

@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    
    [super viewDidLoad];
    
    //创建一个红色的圆形CALayer
    CALayer * layer       = [CALayer layer];
    layer.bounds          = CGRectMake(0, 0, 30, 30);
    layer.position        = CGPointMake(self.view.center.x - 50, self.view.center.y - 50);
    layer.backgroundColor = [UIColor redColor].CGColor;
    layer.cornerRadius    = 15;
    [self.view.layer addSublayer:layer];
    
    //创建一个透明度动画
    CABasicAnimation * animation1 = [CABasicAnimation animationWithKeyPath:@"opacity"];
    animation1.fromValue          = @(0);
    animation1.toValue            = @(1);
    animation1.duration           = 1.5;
    animation1.autoreverses       = YES;
    
    //创建一个缩放动画
    CABasicAnimation * animation2 = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
    animation2.toValue            = @(1.5);
    animation2.fromValue          = @(0.5);
    animation2.duration           = 1.5;
    animation2.autoreverses       = YES;
    
    //创建一个动画组, 将之前创建的透明度动画和缩放动画加入到这个动画组中
    CAAnimationGroup * ani = [CAAnimationGroup animation];
    ani.animations         = @[animation1,animation2];
    ani.duration           = 1.5;
    ani.repeatCount        = MAXFLOAT;
    ani.autoreverses       = YES;
    
    //将动画组添加到layer
    [layer addAnimation:ani forKey:nil];
    
    CAReplicatorLayer * rec = [CAReplicatorLayer layer];
    rec.instanceCount       = 3;
    rec.instanceDelay       = 0.5;
    rec.instanceTransform   = CATransform3DMakeTranslation(50, 0, 0);
    [rec addSublayer:layer];
    [self.view.layer addSublayer:rec];
    
    CAReplicatorLayer * rec2 = [CAReplicatorLayer layer];
    rec2.instanceCount       = 3;
    rec2.instanceDelay       = 0.5;
    rec2.instanceTransform   = CATransform3DMakeTranslation(0, 50, 0);
    [rec2 addSublayer:rec];
    [self.view.layer addSublayer:rec2];
}

@end