Clipping an image with a custom UIBezierPath

问题

I was wondering if someone could point me in the right direction with this problem.

I have a user-created UIBezierPath with several points that have come about by user touches.

I can get these to create shapes on a bog-standard UIView by using the [myPath fill]; function.

What I would ideally like to do is to use the path to create a clipping mask for a UIImage - perhaps as a UiImageView?

I tried changing my UIView to a UIImageView and then changing the function to [myPath addClip]; but for some reason it does not work.

回答1:

You need to create a graphics context, draw your image, and draw your mask using kCGBlendModeDestinationIn. Something like this:

UIGraphicsBeginImageContextWithOptions(size, NO, 0.0); // size is a CGSize of the result you want
[image drawInRect:imageRect];  // image is the UIImage you want to clip, imageRect is the rect in the context where you want your image
[mask drawInRect:rect blendMode:kCGBlendModeDestinationIn alpha:1.0];  // mask is a UIImage containing the mask you drew, rect is the rect in the context where you want your mask - could match imageRect above
UIImage* uiImage = UIGraphicsGetImageFromCurrentImageContext();

来源：https://stackoverflow.com/questions/8783631/clipping-an-image-with-a-custom-uibezierpath