iphone - Animate a UIButton from one image to another -

I saw in Jamie Oliver App, when you click on a button, it's a smooth transition from one size. Does anyone know how this is done? I tried to use some UIView animations, but none of them satisfies my needs

< P> The UI animation alone can not give you that effect .. To get the effect you need to pair with the changes that you are talking about, try it in the following ways you will get what you want ... [UIView startAnimations: @ "zoomin" concurrent RT: nil]; [UIView Set Animation Duration: 0.25]; StarImage.transform = CGF Trans Transform Memory Cache (2.5, 2.5); [UIView commitAnimations]; [UIView Start Permissions: @ "Zoom Out" Reference: Zero]; [UIView Set Animation Duration: 0.25]; StarImage.transform = CGF TransFormsMacecale (1, 1); [UIView commitAnimations];