Access interim points while UIView is animated

I'm animating an image in an UIImageView. This works just great with Core Animation. Now I want to attach one end of a line permanentely to the center of this UIIMageView. But wit开发者_JS百科h Core Animation I only get the starting point and the end point of the UIImageView. Is there a possibility to access interim points during the animation? I want to extend the functionality to many UIImageViews, which are animated, with a line attached to them. I don't want to create timers to monitor all animations and calculate my own interim points. Does somebody have any suggestions? Thanks!

Bye, Björn

If you're using Core Animation (I'm not sure if this works with strictly UIView-based animation), you should be able to get a particular instantaneous value of your property by looking at the presentationLayer property of your view's backing CALayer. That property exposes a read-only copy of the current set of values as a layer is animating. You can look at this on a display link "timer" and update something else, etc.

I'm having a tough time picturing exactly what you're trying to accomplish overall, but this might get you started.

I found this post, which points to the right direction: http://dbachrach.com/blog/2008/04/instantaneous-frame-of-moving-core-animation-views/ But there's still one problem: this seems to work for CABasicAnimations only, not for the standard animations. Is there a way to access interim points when using standard animations ([UIView beginAnimation] ...)?? Thanks.

Björn