How to specify an beginTime for an animation by using CFTimeInterval?

Question

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.

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

Answer 1

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; 

Answer 2

You first need to convert to the layer's timespace like so:

let currentLayerTime = myLayer.convertTime(CACurrentMediaTime(), from: nil) 

Then you can set the beginTime relative to the layer's now time. For instance, to make an animation begin in 2s:

myAnimation.beginTime = currentLayerTime + 2 

You'll also likely want to set the fillMode to .backwards, so that you can set the final property value before you add the animation:

myAnimation.fillMode = .backwards myLayer.someProperty = someFinalValue myLayer.addAnimation(myAnimation, forKey: "myAnimationName")