#38: Gesture Recognizer Basics πŸ‘†


Gesture Recognizers are an powerful way to build interactions into your app. Let's look at the basics with a couple of example use cases:

Two Finger Long Press

Here we'll build a gesture that fires when the user touches the screen with two fingers for 1 second.

func handleLongPressGesture(gr: UILongPressGestureRecognizer) {

let longPressGR = UILongPressGestureRecognizer(
  target: self, 
  action: "handleLongPressGesture:"

// we allow user some 'wiggle' so the recognizer
// doesn't fail if they move slightly while touching

longPressGR.allowableMovement = 80

longPressGR.minimumPressDuration = 1 // in seconds
longPressGR.numberOfTouchesRequired = 2


Make a View Draggable

Ever wanted to enable a view to be dragged around the screen? A pan gesture recognizer does the trick:

func handlePanGesture(gr: UIPanGestureRecognizer) {
  guard gr.state != .Ended && gr.state != .Failed else { return }

  gr.view!.center = gr.locationInView(gr.view!.superview!)

let panGR = UIPanGestureRecognizer(
  target: self,
  action: "handlePanGesture:"

panGR.minimumNumberOfTouches = 1
panGR.maximumNumberOfTouches = 1