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

Answer 2

can be done with UIViewController's presentModalViewController:animated: and setting the modalTransistionStyle to UIModalTransitionStylePartialCurl. See apple's docs.

Answer 3

@IBAction func curl(_ sender: Any, forEvent event: UIEvent) {
    
    if b == 1 {
    UIView.transition(with: imageview, duration: 1.5, options: .transitionCurlUp, animations: {self.imageview.isHidden = true}, completion: nil)
        b = 2
    }
    else if b == 2
    {
        self.imageview.isHidden  = false
        UIView.transition(with: imageview, duration: 1.5, options: .transitionCurlDown, animations: {self.imageview.isHighlighted = true}, completion: nil)
        b = 1
    }
}