How do I set up an UIScreenEdgePanGestureRecognizer using Interface Builder?

Question

I can\'t get UIScreenEdgePanGestureRecognizer to work when I create when I add it to my view controller using Interface Builder, so I\'m asking here to establish wh

Answer 1

Xcode isn’t always a good neighbor. Sorry.

override func viewDidLoad() {
    super.viewDidLoad()

    let panGesture = UIScreenEdgePanGestureRecognizer(target: self, action: "panAction:")
    panGesture.edges = .Left
    view.addGestureRecognizer(panGesture)
}


func panAction(sender: UIScreenEdgePanGestureRecognizer) {
    let translation = sender.translationInView(sender.view!)

    println("Trans:\(translation)")
}

Answer 2

It seems that there is a bug in Xcode 6.4’s interface builder and Swift. Also, Thomas LIU’s answer was also correct: it seems to be necessary to set the .edge property in code, rather than with Interface Builder.

Even though there are edge checkboxes in IB, they seem to be ignored.

I solved it this way: Ctrl-drag from the gesture recognizer to the viewController class to create an IBOutlet:

class ViewController: UIViewController {
    @IBOutlet var leftEdgeGestureRecognizer: UIScreenEdgePanGestureRecognizer!

then, in viewDidLoad:

leftEdgeGestureRecognizer.edges = .Left

and finally, ctrl-drag from the recognizer to create an IBAction

@IBAction func swipeFromLeft(sender: AnyObject) {
        print("===> Swipe from left edge.\n")
}

Answer 3

I have tried it in Xcode 7.0 Beta 4 (7A165t) and it's still a bug. Adding the Screen Edge Pan Gesture Recognizer via Interface Builder doesn't call the referenced IBAction, however adding it programmatically like this works fine:

class ViewController: UIViewController, UIGestureRecognizerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        let edgeGestureRecognizer = UIScreenEdgePanGestureRecognizer(target: self, action: "userSwipedFromEdge:")
        edgeGestureRecognizer.edges = UIRectEdge.Left
        edgeGestureRecognizer.delegate = self
        self.view.addGestureRecognizer(edgeGestureRecognizer)
    }

    func userSwipedFromEdge(sender: UIScreenEdgePanGestureRecognizer) {
        if sender.edges == UIRectEdge.Left {
            print("It works!")
        }
    }
}

Hint: Don't forget to add the UIGestureRecognizerDelegate protocol to your class. Otherwise you'll get an error at edgeGestureRecognizer.delegate = self

Answer 4

To make sure that multiple gesture recognizers can work together you have to implement the method shouldRecognizeSimultaneouslyWithGestureRecognizer and return true:

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool {
    return true
}

Sorry for the Swift code but you should get the idea.

This method must be implemented even if you are using a single gesture recognizer because the view can have its own (system) recognizers, such as MKMapView.

Answer 5

It can be considered as a bug, but actually, here is something useful:

"After creating a screen edge pan gesture recognizer, assign an appropriate value to the edges property before attaching the gesture recognizer to your view."

https://developer.apple.com/library/prerelease/ios/documentation/UIKit/Reference/UIScreenEdgePanGestureRecognizer_class/index.html

This requirement only apply to UIScreenEdgePanGestureRecognizer, so I think that's why Xcode make it wrong, it must be implemented as the normal sequence, alloc->init->attach->set value. It will work to all other GestureRecongnizer but not UIScreenEdgePanGestureRecognizer.

Answer 6

Facing same issue from long. Its a xcode bug, its better to add it programmatically.