如何通过使用CFTimeInterval为动画指定beginTime？

问题描述

据我了解，beginTime可以用来表示嘿，从正好12:00开始。但是我如何用CFTimeInterval类型告诉这个呢？我以为这只是指定秒数的一种浮点值。

For my understanding, beginTime can be used to say "hey, start at exactly 12:00 'o clock". But how would I tell this with an CFTimeInterval type? I thought that this one is nothing more than a kind of "float" value to specify seconds.

否则指定的timeOffset属性的区别是什么在CAMediaTiming协议中？

Or what else would be then the difference to the timeOffset property that is specified in CAMediaTiming protocol?

推荐答案

我在文档中错过的内容：beginTime在核心动画绝对时间中，因此您必须获取当前时间并从中指定偏移量：

What I missed in the docs: beginTime is in "core animation absolute time" so you've to get the current time and specify your offset from that:

// Start in 5 seconds
theAnimation.beginTime = CACurrentMediaTime() + 5;

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