Instance Method

canPrevent(_:)

Overridden to indicate that the receiver can prevent the specified gesture recognizer from recognizing its gesture.

Declaration

func canPrevent(_ preventedGestureRecognizer: UIGestureRecognizer) -> Bool

Parameters

preventedGestureRecognizer

An instance of a subclass of UIGestureRecognizer.

Return Value

true to indicate that the receiver can block preventedGestureRecognizer from recognizing its gesture, otherwise false.

Discussion

Overriding these methods enables the same behavior as implementing the UIGestureRecognizerDelegate methods gestureRecognizerShouldBegin(_:) and gestureRecognizer(_:shouldReceive:). However, by overriding them, subclasses can define class-wide prevention rules. For example, a UITapGestureRecognizer object never prevents another UITapGestureRecognizer object with a higher tap count.

See Also

Methods for Subclasses

func touchesBegan(Set<UITouch>, with: UIEvent)

Sent to the gesture recognizer when one or more fingers touch down in the associated view.

func touchesMoved(Set<UITouch>, with: UIEvent)

Sent to the gesture recognizer when one or more fingers move in the associated view.

func touchesEnded(Set<UITouch>, with: UIEvent)

Sent to the gesture recognizer when one or more fingers lift from the associated view.

func touchesCancelled(Set<UITouch>, with: UIEvent)

Sent to the gesture recognizer when a system event (such as an incoming phone call) cancels a touch event.

func touchesEstimatedPropertiesUpdated(Set<UITouch>)

Sent to the gesture recognizer when the estimated properties for a touch have changed so that they are no longer estimated, or an update is no longer expected.

func reset()

Overridden to reset internal state when a gesture recognition attempt completes.

func ignore(UITouch, for: UIEvent)

Tells the gesture recognizer to ignore a specific touch of the given event.

func canBePrevented(by: UIGestureRecognizer) -> Bool

Overridden to indicate that the specified gesture recognizer can prevent the receiver from recognizing a gesture.

func shouldRequireFailure(of: UIGestureRecognizer) -> Bool

Overridden to indicate that the receiver requires the specified gesture recognizer to fail.

func shouldBeRequiredToFail(by: UIGestureRecognizer) -> Bool

Overridden to indicate that the receiver should be required to fail by the specified gesture recognizer.

func ignore(UIPress, for: UIPressesEvent)

Tells the gesture recognizer to ignore a specific press of the given event.

func pressesBegan(Set<UIPress>, with: UIPressesEvent)

Sent to the receiver when a physical button is pressed in the associated view.

func pressesChanged(Set<UIPress>, with: UIPressesEvent)

Sent to the receiver when the force of the press has changed in the associated view.

func pressesEnded(Set<UIPress>, with: UIPressesEvent)

Sent to the receiver when a button is released from the associated view.

func pressesCancelled(Set<UIPress>, with: UIPressesEvent)

Sent to the receiver when a system event (such as a low-memory warning) cancels a press event.