水波动画的实现

   CAMediaTimingFunction *defaultCurve = [CAMediaTimingFunctionfunctionWithName:kCAMediaTimingFunctionDefault];

    

    CAAnimationGroup *animationGroup = [CAAnimationGroupanimation];

    animationGroup.duration =self.animationDuration +self.pulseInterval;

    animationGroup.repeatCount =INFINITY;

    animationGroup.removedOnCompletion =NO;

    animationGroup.timingFunction = defaultCurve;

    

    CABasicAnimation *scaleAnimation = [CABasicAnimationanimationWithKeyPath:@"transform.scale.xy"];

    scaleAnimation.fromValue =@0.0;

    scaleAnimation.toValue =@1.0;

    scaleAnimation.duration =self.animationDuration;

    

    CAKeyframeAnimation *opacityAnimation = [CAKeyframeAnimationanimationWithKeyPath:@"opacity"];

    opacityAnimation.duration =self.animationDuration;

    opacityAnimation.values =@[@0.45, @0.45,@0];

    opacityAnimation.keyTimes =@[@0, @0.2,@1];

    opacityAnimation.removedOnCompletion =NO;

    

    NSArray *animations =@[scaleAnimation, opacityAnimation];

    

    animationGroup.animations = animations;

    

    [selfaddAnimation:animationGroupforKey:@"pulse"];