I want to do something similar to iPhone's photo viewer. When you single tap, the UI bars disappear after a short delay. When you double tap, it zooms in. But I don't want anything to happen on double tap because I haven't yet implemented zooming in.

Anyone know how to do this?

[This post] didn't really help. Unless you tell me it's necessary to subclass `UIGestureRecognizer`. Then, I think I could figure it out. Anyone have any examples?