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#38: Gesture Recognizer Basics πŸ‘†

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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) {
  sendHeartbeat()
}

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

digitalTouchView.addGestureRecognizer(longPressGR)

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

moveableView.addGestureRecognizer(panGR)