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一个心跳的动画

- (void)viewDidLoad {    [super viewDidLoad];    UIButton *heart = [[UIButton alloc]initWithFrame:CGRectMake(self.view.frame.size.width * 0.5 - 25, 200, 50, 50)];    [self.view addSubview:heart];    [heart setImage:[UIImage imageNamed:@"5_heart"] forState:UIControlStateNormal];    [heart setImage:[UIImage imageNamed:@"5_heart_clicked"] forState:UIControlStateSelected];    [heart addTarget:self action:@selector(heartButtonClick:) forControlEvents:UIControlEventTouchUpInside];}/** *  心跳 */- (void)heartButtonClick:(UIButton *)button{    button.selected = !button.selected;    CAKeyframeAnimation *k = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];    k.values =  @[@(0.1),@(1.0),@(1.5)];    k.keyTimes = @[@(0.0),@(0.5),@(0.8),@(1.0)];    k.calculationMode = kCAAnimationLinear;    [button.layer addAnimation:k forKey:@"SHOW"];}