gestureRecognizer(_:shouldRequireFailureOf:)
Asks the delegate if a gesture recognizer should require another gesture recognizer to fail.
Declaration
optional func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> BoolParameters
- gestureRecognizer:
An instance of a subclass of the abstract base class Uigesturerecognizer. This is the object sending the message to the delegate.
- otherGestureRecognizer:
An instance of a subclass of the abstract base class Uigesturerecognizer.
Mentioned in
Return Value
true to set up a dynamic failure requirement between gestureRecognizer and otherGestureRecognizer. The default implementation returns false—gestureRecognizer doesn’t require otherGestureRecognizer to fail.
Discussion
This method is called once per attempt to recognize, so failure requirements can be determined lazily and may be set up between recognizers across view hierarchies. Note that returning true is guaranteed to set up the failure requirement; returning false, on the other hand, isn’t guaranteed to prevent or remove a failure requirement because otherGestureRecognizer might make itself a failure requirement by using its own subclass or delegate methods.