Core animation equivalent for built-in UIView animation

I'm looking for an equivalent core animation for the following UIView animation?

[UIView animateWithDuration:0.25 animations:^(void) {
                cell.frame = newCellFrame;

            } completion:^(BOOL finished) {
                [UIView animateWithDuration:0.25 animation:^(void) {
                    cell.frame = finalCellFrame;
                }];                    
            }];

What I would like to know in particular is how you mimic the "c开发者_如何转开发ompletion" part of this animation with core animation. Is the only option to use core animation delegation or is there a solution as elegant as the above code snippet?

In CoreAnimation it's done with delegates. You can set a delegate on your CAAnimation/CABasicAnimation instance, and the animation will make animationDidStart: and animationDidStop:finished: callbacks to you.