You have to create your own UIView's subclass and add it as overlay.
In the method -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
you can do everything you want to do when the screen is touched.
I have done this in my project. I have implemented design of the VideoOverlay( the UIView's subclass) in Interface Builder. It is much easier when you have to add other elements that user have to interact with.
mxg
2010-03-22 12:29:16