How to debug UIGestureRecognizers

Question

I have a hierarchy of views with different UIGestureRecognizers. Every now and then one of them stops working, and I am looking for an efficient way to debug this. Due to the passive nature of UIGestureRecognizers in general, I always find them hard to debug. If one stops working, the two things that I can think of would be to

• Examine the view hierarchy to make sure another view isn't blocking the touch
• Override touchesBegan:withEvent: on all relevant views to try to track down the passing of a touch

These sometimes don't cut it, though, as is the current situation where I have a UITapGestureRecognizer that sometimes (I believe after presenting and dismissing views) stops working while the app is running.

Answer 1

I would recommend checking out the little known (IME) property gestureRecognizers on UITouch, that may be enough to help you. You can also combine this with overriding the UIWindow and UIApplication methods called sendEvent to gain more visibility into the sequence of events wrt. touch handling. (No pun intended.)