Observing animated property changes in a CALayer

Question

I have a CABasicAnimation that animating a property of a CALayer e.g. bounds.origin. I want to be able to observe the property changing ov

Answer 1

Try using CADisplayLink, which is designed to stay in sync with the animation loop. More info: https://ashfurrow.com/blog/animating-views-with-cadisplaylink/

Answer 2

I think you've named all of the possibilities. In fact, I wasn't even aware of #2 and #3 and I wrote the book on Core Animation. ;-)

KVO is not available for these properties. Would be nice if it were, but I believe the reason for this has to do with the overhead it would take. The value would update very frequently and have to call back to any observers.

Anyhow, I've found the NSTimer to be the most reliable approach, but now I'm not sure from what you've said. What makes you think that the timer is out of sync? Why is it difficult get the timer only to fire when the animation is running? Can't you just check for the condition you want in the timer callback and then do nothing if the condition is not met?

Best Regards.