Fold/curl edge of UIImageView

Question

I need to fold/unfold the edge of UIImageView to mark as a favorite. I searched across multiple sites, but have not found anything about it.

I attached some example images, and, if possible, with animation effect.

Answer 1

One way to do it would be to animate the view usign OpenGL. There is a nice library for that called XBPageCurl

However, you could achieve a much lighter solution by creating a mask for the curl effect and animate your view while transitioning to it. Here is what it would look like

[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.3];

UIImage *maskedImage = [yourImage imageMaskedWithImage:yourMask];
[yourImageView setImage:maskedImage];

[UIView commitAnimations];

To know how to mask an image, have a look here http://mobiledevelopertips.com/cocoa/how-to-mask-an-image.html