the image property on the UIImageView class has the following docs:
“If the animationImages property contains a value other than nil, the contents of this property are not used.”
So the trick to hold on the last frame of an animation in iOS4 is to first set the image property to that last frame (while animationImages is still nil), then set the animationImages property and call startAnimating. When the animation completes, the image property is then displayed. No callback/delegate needed.