How can I implement “drag right to dismiss” a View Controller that's in a navigation stack?

Question

By default, if you drag right from the left edge of the screen, it will drag away the ViewController and take it off the stack.

I want to extend this functionality t

Answer 1

Swipe Right to dismiss the View Controller

Swift 5 Version - (Also removed the gesture recognition when swiping from right - to - left)

Important - In ‘Attributes inspector’ of VC2, set the ‘Presentation’ value from ‘Full Screen’ to ‘Over Full Screen’. This will allow VC1 to be visible during dismissing VC2 via gesture — without it, there will be black screen behind VC2 instead of VC1.

class ViewController: UIGestureRecognizerDelegate, UINavigationControllerDelegate {

    var initialTouchPoint: CGPoint = CGPoint(x: 0, y: 0)

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.interactivePopGestureRecognizer?.delegate = self
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
        view.addGestureRecognizer(panGesture)
    }

    @objc func handlePanGesture(_ sender: UIPanGestureRecognizer) {
        let touchPoint = sender.location(in: self.view?.window)
        let percent = max(sender.translation(in: view).x, 0) / view.frame.width
        let velocity = sender.velocity(in: view).x

        if sender.state == UIGestureRecognizer.State.began {
            initialTouchPoint = touchPoint
        } else if sender.state == UIGestureRecognizer.State.changed {
            if touchPoint.x - initialTouchPoint.x > 0 {
                self.view.frame = CGRect(x: touchPoint.x - initialTouchPoint.x, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height)
            }
        } else if sender.state == UIGestureRecognizer.State.ended || sender.state == UIGestureRecognizer.State.cancelled {

            if percent > 0.5 || velocity > 1000 {
                navigationController?.popViewController(animated: true)
            } else {
                UIView.animate(withDuration: 0.3, animations: {
                    self.view.frame = CGRect(x: 0, y: 0, width: self.view.frame.size.width, height: self.view.frame.size.height)
                })
            }
        }
    }
}

Hope this helps. Feel free to suggest changes if necessary.

Answer 2

I think this is easier than the suggested solution and also works for all viewControllers inside that navigation and also for nested scrollviews.

https://stackoverflow.com/a/58779146/8517882

Just install the pod and then use EZNavigationController instead of UINavigationController to have this behavior on all view controllers inside that navigation controller.

Answer 3

Made a demo project in Github
https://github.com/rishi420/SwipeRightToPopController

I've used UIViewControllerAnimatedTransitioning protocol

From the doc:

// This is used for percent driven interactive transitions, as well as for container controllers ...

Added a UIPanGestureRecognizer to the controller's view. This is the action of the gesture:

func handlePanGesture(panGesture: UIPanGestureRecognizer) {

    let percent = max(panGesture.translationInView(view).x, 0) / view.frame.width

    switch panGesture.state {

    case .Began:
        navigationController?.delegate = self
        navigationController?.popViewControllerAnimated(true)

    case .Changed:
        percentDrivenInteractiveTransition.updateInteractiveTransition(percent)

    case .Ended:
        let velocity = panGesture.velocityInView(view).x

        // Continue if drag more than 50% of screen width or velocity is higher than 1000
        if percent > 0.5 || velocity > 1000 {
            percentDrivenInteractiveTransition.finishInteractiveTransition()
        } else {
            percentDrivenInteractiveTransition.cancelInteractiveTransition()
        }

    case .Cancelled, .Failed:
        percentDrivenInteractiveTransition.cancelInteractiveTransition()

    default:
        break
    }
}

Steps:

1. Calculate the percentage of drag on the view
2. .Begin: Specify which segue to perform and assign UINavigationController delegate. delegate will be needed for InteractiveTransitioning
3. .Changed: UpdateInteractiveTransition with percentage
4. .Ended: Continue remaining transitioning if drag 50% or more or higher velocity else cancel
5. .Cancelled, .Failed: cancel transitioning

References:

1. UIPercentDrivenInteractiveTransition
2. https://github.com/visnup/swipe-left
3. https://github.com/robertmryan/ScreenEdgeGestureNavigationController
4. https://github.com/groomsy/custom-navigation-animation-transition-demo

Answer 4

Swift 4 version of the accepted answer by @Warif Akhand Rishi

Even though this answer does work there are 2 quirks that I found out about it.

1. if you swipe left it also dismisses just as if you were swiping right.
2. it's also very delicate because if even a slight swipe is directed in either direction it will dismiss the vc.

Other then that it definitely works and you can swipe either right or left to dismiss.

class ViewController: UIGestureRecognizerDelegate, UINavigationControllerDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        navigationController?.interactivePopGestureRecognizer?.delegate = self
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture(_:)))
        view.addGestureRecognizer(panGesture)
    }

    @objc func handlePanGesture(_ gesture: UIPanGestureRecognizer){

        let interactiveTransition = UIPercentDrivenInteractiveTransition()

        let percent = max(gesture.translation(in: view).x, 0) / view.frame.width

        switch gesture.state {

        case .began:
            navigationController?.delegate = self

            // *** use this if the vc is PUSHED on the stack **
            navigationController?.popViewController(animated: true)

            // *** use this if the vc is PRESENTED **
            //navigationController?.dismiss(animated: true, completion: nil)

        case .changed:
            interactiveTransition.update(percent)

        case .ended:
            let velocity = gesture.velocity(in: view).x

            // Continue if drag more than 50% of screen width or velocity is higher than 1000
            if percent > 0.5 || velocity > 1000 {
                interactiveTransition.finish()
            } else {
                interactiveTransition.cancel()
            }

        case .cancelled, .failed:
            interactiveTransition.cancel()

        default:break
        }
    }
}

Answer 5

Create a pan gesture recogniser and move the interactive pop gesture recogniser's targets across.

Add your recogniser to the pushed view controller's viewDidLoad and voila!

let popGestureRecognizer = self.navigationController!.interactivePopGestureRecognizer!
if let targets = popGestureRecognizer.value(forKey: "targets") as? NSMutableArray {
  let gestureRecognizer = UIPanGestureRecognizer()
  gestureRecognizer.setValue(targets, forKey: "targets")
  self.view.addGestureRecognizer(gestureRecognizer)
}

Answer 6

You need to investigate the interactivePopGestureRecognizer property of your UINavigationController.

Here is a similar question with example code to hook this up.

UINavigationController interactivePopGestureRecognizer working abnormal in iOS7