Definition - What does Gesture Recognizer mean?
Techopedia explains Gesture Recognizer
Existing gesture recognizers include support for pinching in and out, panning and dragging and various types of quick taps. There is also a class for a "long press" or "touch and hold" input, as well as rotating and swiping actions on the touchscreen.
Although the gesture recognizer class allows the development of custom responses, experts advise developers to adhere to normal standards expected by users. Changing responses within a given application can profoundly confuse one of the most important, intuitive aspects of the iOS user interface, which takes users some time to learn and should be as easy as possible to understand.