Iphone 如何在ipad中按顺序播放动画

我有两个层的动画，第一层和第二层，每个层有不同的路径。所以，我想知道怎样才能按顺序演奏。首先播放第1层的动画，然后播放第2层

这是我的两个动画代码

第1层

    CALayer *layer1 = [CALayer layer];
    [self.layer addSublayer:layer1];
    CAKeyframeAnimation *animation1 = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    layer1.contents = (id)image1.CGImage;
    layer1.anchorPoint = CGPointZero;
    layer1.frame = CGRectMake(0.0f, 0.0f, image1.size.width, image1.size.height);
    animation1.path = path1;
    animation1.duration = 2.0f;
    animation1.calculationMode = kCAAnimationLinear;
    [layer1 addAnimation:animation1 forKey:@"position"];

第2层

    CALayer *layer2 = [CALayer layer];
    [self.layer addSublayer:layer2];
    CAKeyframeAnimation *animation2 = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    layer2.contents = (id)image2.CGImage;
    layer2.anchorPoint = CGPointZero;
    layer2.frame = CGRectMake(0.0f, 0.0f, image2.size.width, image2.size.height);
    animation2.path = path2;
    animation2.duration = 2.0f;
    animation2.calculationMode = kCAAnimationLinear;
    [layer2 addAnimation:animation2 forKey:@"position"];

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为第一个动画设置代理，并在

animationDidStop:finished:

delegate方法中启动第二个动画