Morphing with CoreAnimation

Question

I am creating an Navigation Button. When user presses it, the image of the button should change, reflecting it's state (e.g. menu opened / closed). I decided to do a morphing-liek animation for this. Is it possible to implement with CoreAnimation? What animation type do I need to use?
I attached the picture to clearly illustrate what I want. Also, you might see these animations in "Pimp My Ride" show.

Answer 1

You can use animationImages property of UIImageView for this, like this:

myImageView = [[UIImageView alloc] initWithFrame:myImageViewbounds];

//Add images which will be used for the animation using an array. These should exist in your project and bundle already.
myImageView.animationImages =  @[[UIImage imageNamed:@"1.png"], [UIImage imageNamed:@"2.png"],[UIImage imageNamed:@"3.png"], [UIImage imageNamed:@"4.png"],[UIImage imageNamed:@"5.png"]];

//Set the duration of the entire animation
myImageView.animationDuration = 0.5;

//Set the repeat count. If you don't set that value, by default will be a loop (infinite)
myImageView.animationRepeatCount = 1;

//Start the animation
[myImageView startAnimating];

To ensure smooth morphing like transition you may check out GPUImage which has many great blur filters. Ideally you should be able to wrap a blur animation between two image animations to achieve what you want.