There are two UIViews of similar size. UIView one (A) is originally on top of UIView two (B). When I try to perform a CABasicAnimation transform.rotation.y on A's layer:

CABasicAnimation *rotateAnimation = [CABasicAnimation animationWithKeyPath:@"transform.rotation.y"];
CGFloat startValue = 0.0;
CGFloat endValue = M_PI;
rotateAnimation.fromValue = [NSNumber numberWithDouble:startValue];
rotateAnimation.toValue = [NSNumber numberWithDouble:endValue];
rotateAnimation.duration = 5.0;
[CATransaction begin];
[imageA.layer addAnimation:rotateAnimation forKey:@"rotate"];
[CATransaction commit];

During the animation, the animating layer's UIView (A) will be:

1. sent back (A is suddenly behind B)
2. rotating ... passed second half of the animation
3. sent front (A is now on top of B again)

Is there a way to keep A on top of B for the whole animation period? Thanks!

UPDATE: project source is attached: FlipLayer.zip