Tells the responder when a system event (such as a system alert) cancels a touch sequence.
- iOS 2.0+
- tvOS 9.0+
The event to which the touches belong.
UIKit calls this method when it receives a system interruption requiring cancellation of the touch sequence. An interruption is anything that causes the application to become inactive or causes the view handling the touch events to be removed from its window. Your implementation of this method should clean up any state associated with handling the touch sequence. The default implementation of this method forwards the message up the responder chain. When creating your own subclasses, call
super to forward any events that you do not handle yourself. For example,
If you override this method without calling
super (a common use pattern), you must also override the other methods for handling touch events, if only as stub (empty) implementations.