你如何实现＆QUOT;时钟擦拭＆QUOT;在IOS /径向擦拭效果？ [英] How do you achieve a "clock wipe"/ radial wipe effect in iOS?
问题描述
有时你会看到一个时钟擦除动画使用。事情是这样的：
Sometimes you'll see a "clock wipe" animation in use. Something like this:
你将如何实现在iOS设备上的效果？
How would you achieve that effect in iOS?
（注：这个问题是一个枪手。我想分享的技术来创建一个时钟擦拭动画，但这样做没有共享教程的格式，所以我能来最接近的是问一个问题，然后提供了答案。这是故意的，并共享信息，因为我回答了自己其他人可能会发现有用的。请不要投下来我的帖子的一种尝试。）
(Note: This question is a "ringer." I wanted to share a technique for creating a clock wipe animation, but SO does not have a format for sharing tutorials, so the closest I can come is asking a question and then providing the answer. This is deliberate, and an attempt to share information that others might find useful. Please don't down vote my post because I answered it myself.)
推荐答案
答：
您需要创建CAShapeLayer并安装它作为您的视图层口罩。
You'd create CAShapeLayer and install it as a mask on your view's layer.
您会再安装一个弧形成跨越全360度，并有一个半径是这样的中心到角落的距离图像的一半的形状层。你想给它，这是同为半径的线宽。
You'd then install an arc into the shape layer that spanned a full 360 degrees, and had a radius that was half the center-to-corner distance of your image. You'd give it a line width that was the same as the radius.
最后，你会创建一个动画形状图层从0到1.0 strokeEnd属性CABasicAnimation。这将导致形状开始是空的（形象充分屏蔽）和动画面具作为饼片是变得越来越大，直到它在图像的全尺寸。
Finally, you'd create a CABasicAnimation that animates the strokeEnd property of the shape layer from 0 to 1.0. This would cause the shape to start out empty (image fully masked) and animate the mask as a "pie slice" that got bigger and bigger, until it was the full size of the image.
您可以下载在github上一个示例项目，我写了表演工作code这个动画，其他核心动画技术中：
You can download a sample project on github that I wrote that shows working code for this animation, among other Core Animation techniques:
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