UIButton has its center at (0,0), UIImageView at (width/2, height/2). Setting the center of image view to (0,0) show this view correctly at screen like the button.
"[touch locationInView:[self view]]" with button does not work because UIButton do not respond to touches events in ViewController.
Using UIImageView with center (0, 0) and using "cpVect point = [touch locationInView:[self view]]" does work as expected on iPhone and iPad.
I dont use OpenGL/cocos2d too, no need to use "480-...".