Andrew M Andrew M - 5 months ago 18
iOS Question

Touch Event on UIView

Does anyone have any sample code for detecting touches on a dynamically created UIView? I have found some references to touchesBegan but cannot figure out how to implement it...

Answer

A very general way to get touches is to override these methods in a custom UIView subclass:

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

The official docs for these methods is under Responding to Touch Events in the UIResponder class docs (UIView inherits those methods since it's a subclass of UIResponder). Longer and more introductory docs can be found in the Event Handling Guide for iOS.

If you just want to detect a tap (touch-down, then touch-up within your view), it's easiest to add a UIButton as a subview of your view, and add your own custom method as a target/action pair for that button. Custom buttons are invisible by default, so it wouldn't affect the look of your view.

If you're looking for more advanced interactions, it's also good to know about the UIGestureRecognizer class.