形状图层和复制图层的简单搭配使用

// ViewController.h
#import <UIKit/UIKit.h>

@interface ViewController : UIViewController


@end


// ViewController.m
#import "ViewController.h"
#import "UIView+Frame.h"

//屏幕宽高
#define screenW [UIScreen mainScreen].bounds.size.width
#define screenH [UIScreen mainScreen].bounds.size.height

@interface ViewController ()

@end

@implementation ViewController

/*
    主要实现思路:
    1.创建形状图层
    2.创建复制图层
    3.创建透明度动画
    4.创建缩放动画
    5.创建动画组把2个动画添加进去
    6.把动画组添加到形状图层
 */
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    [self setUp];
}

- (void)setUp {

    UIView *animBack = [[UIView alloc] init];
    animBack.width = screenW;
    animBack.height = screenW;
    animBack.center = self.view.center;
    [self.view addSubview:animBack];

    // 形状图层
    CAShapeLayer *shapL = [CAShapeLayer layer];
    shapL.frame = animBack.bounds;
    shapL.fillColor = [UIColor redColor].CGColor;
    shapL.path = [UIBezierPath bezierPathWithOvalInRect:shapL.bounds].CGPath;
//    shapL.path = [UIBezierPath bezierPathWithRect:shapL.bounds].CGPath;
    // 这句代码不加的话,程序一起来，就会出现一个很大的红色的圆
    shapL.opacity = 0;

    // 复制图层
    CAReplicatorLayer *repL = [CAReplicatorLayer layer];
    repL.frame = animBack.bounds;
    // 复制的份数算自己本身一份
    repL.instanceCount = 3;
    // 每一份显示的间隔时间
    repL.instanceDelay = 0.5;
    [animBack.layer addSublayer:repL];
    // 把形状图层添加到复制层中去
    [repL addSublayer:shapL];

    // 添加透明动画
    CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"opacity"];
    anim.fromValue = @(0.3);
    anim.toValue = @(0);

    // 添加放大动画
    CABasicAnimation *anim2  = [CABasicAnimation animationWithKeyPath:@"transform"];
    anim2.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0, 0, 0)];
    anim2.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(1, 1, 0)];

    // 创建动画组
    CAAnimationGroup *groupA = [CAAnimationGroup animation];
    groupA.animations = @[anim, anim2];
    groupA.duration = 3.0;
    groupA.repeatCount = HUGE;
    // 给形状图层添加动画
    [shapL addAnimation:groupA forKey:nil];
}

@end

• 实现效果: