ios - 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 to the entire screen. When the user drags right anywhere, I'd like the same to happen.

I know that I can implement a swipe right gesture and simply call self.navigationController?.popViewControllerAnimated(true)

However, there is no "dragging" motion. I want the user to be able to right-drag the view controller as if it's an object, revealing what's underneath. And, if it's dragged past 50%, dismiss it. (Check out instagram to see what I mean.)

Answer 1

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