Can anyone explain how this is supposed to work as I've been experimenting with it and nothing I do seems to be able to trap the event? I've tried connecting the event in a button in IB and it doesn't trigger. I've even tried subclassing a UIButton and a UIControl and defining my own addAction:target:selector which works with most other events (UIControlEventTouchDown, UIControlEventTouchUpInside etc.) but nothing happens again when I try to trap UIControlEventTouchDragEnter. I've just got a bit of test code that defines a square button and I'm trying to detect a touch that begins outside of the button, when it touches the button.