I am having trouble accomplishing something that I thought was going to be much easier. I am trying to run a method whenever a non transparent part of a picture inside a UIImage touches another non-transparent part of an image contained within a UIImage. I have included an example to help further explain my question. As you can see in the image above, I have two triangles that are both inside a UIImage. The triangles are both PNG pictures. Only the triangle is visible because the background has been made transparent. Both of the UIImages are inside a UIImageView. I want to be able to run a method when the visible part of the triangle touches the visible part of the other triangle. Can someone please help me?