Gesture Recognizers

The UIGestureRecognizer initializers and delegation wrappers make it easy to add gesture recognizers to views. It also uses closures instead of target-action and delegation.

Target-Action Initializers

The following is how you would add a double tap gesture recognizer to your view using one of the custom initializers. As always, we have a closure handler to respond to the gesture’s double tap action.

let doubleTapGesture = UITapGestureRecognizer(tapsRequired: 2) { _ in
    log("double tapped")
}
view.addGestureRecognizer(doubleTapGesture)

These convenience initializers, delegate closures, and closure recognizers have been added to all of the existing concrete subclasses, including:

  • UITapGestureRecognizer
  • UIPinchGestureRecognizer
  • UIRotationGestureRecognizer
  • UISwipeGestureRecognizer
  • UIPanGestureRecognizer
  • UIScreenEdgePanGestureRecognizer
  • UILongPressGestureRecognizer

There is also a method for you to configure a custom gesture recognizer to use closure handlers for recognition:

let myCustomGesture = MyCustomGestureRecognizer()
configure(gesture: myCustomGesture) { _ in
    /// a closure that's called when the gesture has ended
}

Delegation

With convenient extension methods on UIGestureRecognizer and UIView, we can daisy chain an entire gesture cycle, including responding to UIGestureRecognizerDelegate methods.

view
    .addPanGesture() { pan in
        guard pan.state == .ended else { return }
        log("view panned")
    }.shouldBegin() {
        true
    }.shouldRecognizeSimultaneouslyWith {
        $0 === doubleTapGesture
}
  • See more

    Declaration

    Swift

    extension UIGestureRecognizer
  • See more

    Declaration

    Swift

    extension UITapGestureRecognizer
  • See more

    Declaration

    Swift

    extension UILongPressGestureRecognizer
  • See more

    Declaration

    Swift

    extension UIPinchGestureRecognizer
  • See more

    Declaration

    Swift

    extension UIPanGestureRecognizer
  • See more

    Declaration

    Swift

    extension UISwipeGestureRecognizer
  • See more

    Declaration

    Swift

    extension UIRotationGestureRecognizer
  • See more

    Declaration

    Swift

    extension UIScreenEdgePanGestureRecognizer
  • See more

    Declaration

    Swift

    extension UIView

  • This method is a convenience method to add a closure handler to a custom subclass of UIGestureRecognizer. If creating a custom gesture recognizer, you may want to also provide an initializer that takes a completion handler, just as the Closures framework provides for UIKit gesture recognizers.

    An example of an initializer that adds closure support for recognition of custom gesture recognizer:

    class MyCustomGestureRecognizer: UIGestureRecognizer {
    convenience init(handler: @escaping (_ gesture: MyCustomGestureRecognizer) -> Void) {
        self.init()
        configure(target: self, handler: handler)
    }
}

    Declaration

    Swift

    public func configure<T>(gesture: T, handler: @escaping (_ gesture: T) -> Void)
    where T: UIGestureRecognizer

    Parameters

    gesture

    The UIGestureRecognizer that is being configured to use a closure in place of target-action.
    handler

    The closure that will be called when the gesture is recognized.