动画的CALayer的shadowPath财产 [英] Animating CALayer's shadowPath property

问题描述

我知道一个的CALayer的shadowPath使用显式的动画仅仅是动画，但我还是不能得到这个工作。我怀疑，我没有通过 toValue 正确 - 我的理解这必须是一个 ID ，但物业需要CGPathRef。在 UIBezierPath 存储但这似乎没有工作。我使用下面的code测试：

I am aware that a CALayer's shadowPath is only animatable using explicit animations, however I still cannot get this to work. I suspect that I am not passing the toValue properly - as I understand this has to be an id, yet the property takes a CGPathRef. Storing this in a UIBezierPath does not seem to work. I am using the following code to test:

CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"shadowPath"];
theAnimation.duration = 3.0;
theAnimation.toValue = [UIBezierPath bezierPathWithRect:CGRectMake(-10.0, -10.0, 50.0, 50.0)];
[self.view.layer addAnimation:theAnimation forKey:@"animateShadowPath"];

（我用的负值，以确保阴影超出摆在它的顶部视图...层的 masksToBounds 属性设置为 NO ）。

是如何实现的shadowPath的动画？

How is animation of the shadowPath achieved?

更新

问题的近的解决。不幸的是，主要问题是有点粗心的错误...

Problem nearly solved. Unfortunately, the main problem was a somewhat careless error...

我犯的错误是将动画添加到视图控制器的根层，而不是我献给阴影层。此外，@ pe8ter是在正确的 toValue 必须是一个 CGPathRef 转换为 ID （显然，当我因错误层试图在此之前我还没有动画）。动画可与下列code：

The mistake I made was to add the animation to the root layer of the view controller, rather than the layer I had dedicated to the shadow. Also, @pe8ter was correct in that the toValue needs to be a CGPathRef cast to id (obviously when I had tried this before I still had no animation due to the wrong layer mistake). The animation works with the following code:

CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"shadowPath"];
theAnimation.duration = 3.0;
theAnimation.toValue = (id)[UIBezierPath bezierPathWithRect:myRect].CGPath;
[controller.shadowLayer addAnimation:theAnimation forKey:@"shadowPath"];

我AP preciate这是很难从我提供的样品code被发现。希望它还是可以使用的，以人虽然类似的情况。

I appreciate this was difficult to spot from the sample code I provided. Hopefully it can still be of use to people in a similar situation though.

然而，当我尝试并添加行

However, when I try and add the line

controller.shadowLayer.shadowPath = [UIBezierPath bezierPathWithRect:myRect].CGPath;

动画停止工作，并阴影只是跳到最终位置瞬间。文件说，与相同的密钥作为属性添加动画被改变，以覆盖创建设置属性的值时，但shadowPath不能生成隐式动画的动画隐...所以我如何获得新的属性留下来的之后的动画？

推荐答案

首先，您没有设置动画的 fromValue 。

Firstly, you did not set the animation's fromValue.

其次，你是正确的： toValue 接受 CGPathRef ，除了它需要被转换为 ID 。做这样的事情：

Secondly, you're correct: toValue accepts a CGPathRef, except it needs to be cast to id. Do something like this:

theAnimation.toValue = (id)[UIBezierPath bezierPathWithRect:newRect].CGPath;

您还需要，如果你想改变保持动画完成后明确设置图层的 shadowPath 属性。

You'll also need to set the shadowPath property of the layer explicitly if you want the change to remain after animation.

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