iOS Interactive Animation Swift - ios

Question

I cannot for the life understand why this is not working.
Have two VCs: A and B.
I want to swipe right on VC A to reveal VC B but want to make it interactive so that a user can drag between two VCs (like on Instagram home screen when you swipe left and right to go to the Camera and messages). At the moment, it doesn't 'drag'. You can swipe on VC A and it will go to VC B.
Here's my animator object to slide right:
class SlideRightTransitionAnimator: NSObject {
let duration = 0.5
var isPresenting = false
let customInteractiveTransition = CustomInteractiveTransition()
}
// MARK: UIViewControllerTransitioningDelegate
extension SlideRightTransitionAnimator: UIViewControllerTransitioningDelegate {
// Return the animator when presenting a VC
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
isPresenting = true
return self
}
// Return the animator used when dismissing from a VC
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
isPresenting = false
return self
}
// Add the interactive transition for Presentation only
func interactionControllerForPresentation(using animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return customInteractiveTransition.transitionInProgress ? customInteractiveTransition : nil
}
}
// MARK: UIViewControllerTransitioningDelegate
extension SlideRightTransitionAnimator: UIViewControllerAnimatedTransitioning {
// Return how many seconds the transiton animation will take
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return duration
}
// Animate a change from one VC to another
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
// Get reference to our fromView, toView and the container view that we should perform the transition
let container = transitionContext.containerView
let fromView = transitionContext.view(forKey: UITransitionContextViewKey.from)!
let toView = transitionContext.view(forKey: UITransitionContextViewKey.to)!
// Set up the transform we'll use in the animation
let offScreenRight = CGAffineTransform(translationX: container.frame.width, y: 0)
let offScreenLeft = CGAffineTransform(translationX: -container.frame.width, y: 0)
// Start the toView to the right of the screen
if isPresenting {
toView.transform = offScreenLeft
}
// Add the both views to our VC
container.addSubview(toView)
container.addSubview(fromView)
// Perform the animation
UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 1.0, initialSpringVelocity: 1.0, options: [], animations: {
if self.isPresenting {
fromView.transform = offScreenRight
toView.transform = CGAffineTransform.identity
}
else {
fromView.transform = offScreenLeft
toView.transform = CGAffineTransform.identity
}
}, completion: { finished in
// Tell our transitionContext object that we've finished animating
transitionContext.completeTransition(true)
})
}
}
Here's my Interactive Transition Controller
class CustomInteractiveTransition: UIPercentDrivenInteractiveTransition {
weak var viewController : UIViewController!
var shouldCompleteTransition = false
var transitionInProgress = false
var completionSeed: CGFloat {
return 1 - percentComplete
}
func attachToViewController(viewController: UIViewController) {
self.viewController = viewController
setupPanGestureRecognizer(view: viewController.view)
}
private func setupPanGestureRecognizer(view: UIView) {
view.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(handlePanGesture)))
}
func handlePanGesture(gestureRecognizer: UIPanGestureRecognizer) {
let viewTranslation = gestureRecognizer.translation(in: gestureRecognizer.view!.superview!)
var progress = (viewTranslation.x / 200)
progress = CGFloat(fminf(fmaxf(Float(progress), 0.0), 1.0))
switch gestureRecognizer.state {
case .began:
transitionInProgress = true
viewController.dismiss(animated: true, completion: nil)
case .changed:
shouldCompleteTransition = progress > 0.5
update(progress)
case .cancelled, .ended:
transitionInProgress = false
if !shouldCompleteTransition || gestureRecognizer.state == .cancelled {
cancel()
} else {
finish()
}
default:
print("Swift switch must be exhaustive, thus the default")
}
}
}
And lastly the code for VC A:
class ViewControllerA: UITableViewController {
let slideRightTransition = SlideRightTransitionAnimator()
let customInteractiveTransition = CustomInteractiveTransition()
override func viewDidLoad() {
super.viewDidLoad()
// Add a Pan Gesture to swipe to other VC
let swipeGestureRight = UISwipeGestureRecognizer(target: self, action: #selector(swipeGestureRightAction))
swipeGestureRight.direction = .right
view.addGestureRecognizer(swipeGestureRight)
}
// MARK: Pan gestures
func swipeGestureRightAction() {
performSegue(withIdentifier: "showMapSegue", sender: self)
}
// MARK: Prepare for segue
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "showVCB" {
// This gets a reference to the screen that we're about to transition to and from
let toViewController = segue.destination as UIViewController
// Instead of using the default transition animation, we'll ask the segue to use our custom SlideRightTransitionAnimator object to manage the transition animation
toViewController.transitioningDelegate = slideRightTransition
// Add the Interactive gesture transition to the VC
customInteractiveTransition.attachToViewController(viewController: toViewController)
}
}
Thank you in advance!!!

Answer 1

In your viewDidLoad of VC A, you'll want to replace that UISwipeGestureRecognizer with a UIPanGestureRecognizer. Then implement the appropriate .changed state in the gesture handler function.
EDIT: Moreover, to achieve a sliding transition between controllers, I highly recommend using a UIPageViewController instead. That or maybe even a custom UICollectionView solution.

Answer 2

in function handlePanGesture you are taking translation reference from VC A (i.e, gestureRecognizer.view!.superview!)
but instead of that take referance from UIWindow. (i.e, UIApplication.shared.windows.last)
replace gestureRecognizer.view!.superview! with UIApplication.shared.windows.last
it's worked for me.