Swift: Gestures

Sunday, March 22, 2015

Overview

Gestures are a big part of mobile development. This post is all about how to add gestures in iOS dev. You can find more information about gestures on Ray Wenderlich’s site or on ioscreator.

Content

Pan Gesture

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@IBOutlet weak var pannableView: UIView {
    didSet {
        // the ':' means that the method pan will be called with an argument
        let recognizer = UIPanGestureRecognizer(target: self, action: "pan:")
        pannableView.addGestureRecognizer(recognizer)
    }
}
func pan(gesture: UIPanGestureRecognizer) {
    switch gesture.state {
        case .Changed: fallthrough
        case .Ended:
            let translation = gesture.translationInView(pannableView)
            // update anything that depends on the pan gesture using tranlation.x and .y
            gesture.setTranslation(CGPointZero, inView:pannableView)
    }
}

Pinch

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@IBOutlet weak var pinchableView: UIView {
    didSet {
        let recognizer = UIPinchGestureRecognizer(target: self, action: "pinch:")
        pinchableView.addGestureRecognizer(recognizer)
    }
}
func pinch(gesture: UIPinchGestureRecognizer) {
    switch gesture.state {
        case .Began:
        case .Changed:
        case .Ended:
        case .Recognized
    }
    var scale:CGFloat = gesture.scale        // can reset
    var velocity:CGFloat = gesture.velocity  // readonly how fast you pinch
}

Rotate

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@IBOutlet weak var rotatableView: UIView {
    didSet {
        let recognizer = UIRotationGestureRecognizer(target: self, action: "rotate:")
        rotatableView.addGestureRecognizer(recognizer)
    }
}
func rotate(gesture: UIRotationGestureRecognizer) {
    var rotation:CGFloat = gesture.rotation  // can reset
    var velocity:CGFloat = gesture.velocity  // readonly how fast you rotate
}

Swipe

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@IBOutlet weak var swipableView: UIView {
    didSet {
        let recognizer = UISwipeGestureRecognizer(target: self, action: "swipe:")
        rotatableView.addGestureRecognizer(recognizer)
    }
}
func swipe(gesture: UISwipeGestureRecognizer) {
    var direction:UISwipeGestureRecognizerDirection = gesture.direction
    var numberOfTouchesRequired:Int = gesture.numberOfTouchesRequired
}

Tap

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@IBOutlet weak var tapableView: UIView {
    didSet {
        let recognizer = UITapGestureRecognizer(target: self, action: "tap:")
        rotatableView.addGestureRecognizer(recognizer)
    }
}
func tap(gesture: UITapGestureRecognizer) {
    var numberOfTapsRequired:Int = gesture.numberOfTapsRequired // single tap, double tap, etc
    var numberOfTouchesRequired:Int = gesture.numberOfTouchesRequired
}

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