呼吸动画

CALayer *layer = [CALayer layer];
layer.position = CGPointMake(kHeartSizeWidth/2.0f, kHeartSizeHeight/2.0f);
layer.bounds = CGRectMake(0, 0, kHeartSizeWidth/2.0f, kHeartSizeHeight/2.0f);
layer.backgroundColor = [UIColor clearColor].CGColor;
layer.contents = (__bridge id _Nullable)([UIImage imageNamed:@"breathImage"].CGImage);
layer.contentsGravity = kCAGravityResizeAspect;
[self.heartView.layer addSublayer:layer];

CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];
animation.values = @[@1.f, @1.4f, @1.f];
animation.keyTimes = @[@0.f, @0.5f, @1.f];
animation.duration = 1; //1000ms
animation.repeatCount = FLT_MAX;
animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
[animation setValue:kBreathAnimationKey forKey:kBreathAnimationName];
[layer addAnimation:animation forKey:kBreathAnimationKey];

[CAMediaTimingFunction functionWithControlPoints:0.33 :0 :0.67 :1]

CALayer *breathLayer = [CALayer layer];
breathLayer.position = layer.position;
breathLayer.bounds = layer.bounds;
breathLayer.backgroundColor = [UIColor clearColor].CGColor;
breathLayer.contents = (__bridge id _Nullable)([UIImage imageNamed:@"breathImage"].CGImage);
breathLayer.contentsGravity = kCAGravityResizeAspect;
//        [self.heartView.layer addSublayer:breathLayer];
[self.heartView.layer insertSublayer:breathLayer below:layer];
``` 

> 这里用的是放在 呼吸layer后边 如果想放在呼吸layer前边 就把里面注释打开 然后注掉 inert那行代码

动画组 包含 放大 渐变

``` objc
//缩放
CAKeyframeAnimation *scaleAnimation = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];
scaleAnimation.values = @[@1.f, @2.4f];
scaleAnimation.keyTimes = @[@0.f,@1.f];
scaleAnimation.duration = animation.duration;
scaleAnimation.repeatCount = FLT_MAX;
scaleAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
//透明度
CAKeyframeAnimation *opacityAnimation = [CAKeyframeAnimation animation];
opacityAnimation.keyPath = @"opacity";
opacityAnimation.values = @[@1.f, @0.f];
opacityAnimation.duration = 0.4f;
opacityAnimation.keyTimes = @[@0.f, @1.f];
opacityAnimation.repeatCount = FLT_MAX;
opacityAnimation.duration = animation.duration;
opacityAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];

//动画组
CAAnimationGroup *scaleOpacityGroup = [CAAnimationGroup animation];
scaleOpacityGroup.animations = @[scaleAnimation, opacityAnimation];
scaleOpacityGroup.removedOnCompletion = NO;
scaleOpacityGroup.fillMode = kCAFillModeForwards;
scaleOpacityGroup.duration = animation.duration;
scaleOpacityGroup.repeatCount = FLT_MAX;
[breathLayer addAnimation:scaleOpacityGroup forKey:kBreathScaleName];

- (void)shakeAnimation {
 CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.scale"];
 animation.values = @[@1.0f, @0.8f, @1.f];
 animation.keyTimes = @[@0.f,@0.5f, @1.f];
 animation.duration = 0.35f;
 animation.timingFunctions = @[[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]];
 [self.heartView.layer addAnimation:animation forKey:@""];
}