UIGestureRecognizer is an abstract base class for concrete gesture-recognizer classes. A gesture-recognizer object—or, simply, a gesture recognizer—decouples the logic for recognizing a gesture and acting on that recognition. When one of these objects recognizes a common gesture or, in some cases, a change in the gesture, it sends an action message to each designated target object. UIGestureRecognizer that looks for single or multiple taps. For the gesture to be recognized, the specified number of fingers must tap the view a specified number of times.