interactive viewController using pan Gesture - swift

Question

everyone i've been tearing out my hair trying to find a solution to an interactive view controller transition where you use the pan gesture in the downward direction to bring a full screen view controller from the top to the bottom. Has anyone run across or created any code like this. Below is my code. I already have the dismiss gesture down but cant figure out how to present the view controller by swiping down on the screen. PLEASE HELP!!!
import UIKit
class ViewController: UIViewController {
let interactor = Interactor()
var interactors:Interactor? = nil
let Mview = ModalViewController()
let mViewT: ModalViewController? = nil
var presentedViewControllers: UIViewController?
override func viewDidLoad() {
Mview.transitioningDelegate = self
Mview.modalPresentationStyle = .FullScreen
}
#IBAction func cameraSlide(sender: UIPanGestureRecognizer) {
let percentThreshold:CGFloat = 0.3
// convert y-position to downward pull progress (percentage)
let translation = sender.translationInView(Mview.view)
let verticalMovement = translation.y / UIScreen.mainScreen().bounds.height
let downwardMovement = fmaxf(Float(verticalMovement), 0.0)
let downwardMovementPercent = fminf(downwardMovement, 1.0)
let progress = CGFloat(downwardMovementPercent)
guard let interactor = interactors else { return }
switch sender.state {
case .Began:
interactor.hasStarted = true
self.presentViewController(Mview, animated: true, completion: nil)
case .Changed:
interactor.shouldFinish = progress > percentThreshold
interactor.updateInteractiveTransition(progress)
case .Cancelled:
interactor.hasStarted = false
interactor.cancelInteractiveTransition()
case .Ended:
interactor.hasStarted = false
if !interactor.shouldFinish {
interactor.cancelInteractiveTransition()
} else {
interactor.finishInteractiveTransition()
} default:
break
}
}
}
extension ViewController: UIViewControllerTransitioningDelegate {
func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return DismissAnimator()
}
func interactionControllerForDismissal(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return interactor.hasStarted ? interactor : nil
}
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return PresentAnimator()
}
func interactionControllerForPresentation(animator: UIViewControllerAnimatedTransitioning) -> UIViewControllerInteractiveTransitioning? {
return interactor.hasStarted ? interactor : nil
}
}
class PresentAnimator: NSObject {
}
extension PresentAnimator: UIViewControllerAnimatedTransitioning
{
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
return 1.0
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
guard
let fromVC2 = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey),
let toVC2 = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey),
let containerView2 = transitionContext.containerView() else {return}
let initialFrame = transitionContext.initialFrameForViewController(fromVC2)
toVC2.view.frame = initialFrame
toVC2.view.frame.origin.y = -initialFrame.height * 2
containerView2.addSubview(fromVC2.view)
containerView2.addSubview(toVC2.view)
let screenbounds = UIScreen.mainScreen().bounds
let Stage = CGPoint(x: 0, y: 0)
let finalFrame = CGRect(origin: Stage, size: screenbounds.size)
UIView.animateWithDuration(transitionDuration(transitionContext), animations: {
toVC2.view.frame = finalFrame
}, completion: { _ in transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
}
)
}
}
class ModalViewController: UIViewController {
let interactors = Interactor()
var interactor:Interactor? = nil
#IBAction func close(sender: UIButton) {
dismissViewControllerAnimated(true, completion: nil)
}
#IBAction func handleGesture(sender: UIPanGestureRecognizer) {
let percentThreshold:CGFloat = 0.3
// convert y-position to downward pull progress (percentage)
let translation = sender.translationInView(self.view)
let verticalMovement = translation.y / -view.bounds.height * 2
let downwardMovement = fmaxf(Float(verticalMovement), 0.0)
let downwardMovementPercent = fminf(downwardMovement, 1.0)
let progress = CGFloat(downwardMovementPercent)
guard let interactor = interactor else { return }
switch sender.state {
case .Began:
interactor.hasStarted = true
dismissViewControllerAnimated(true, completion: nil)
case .Changed:
interactor.shouldFinish = progress > percentThreshold
interactor.updateInteractiveTransition(progress)
case .Cancelled:
interactor.hasStarted = false
interactor.cancelInteractiveTransition()
case .Ended:
interactor.hasStarted = false
if !interactor.shouldFinish {
interactor.cancelInteractiveTransition()
} else {
interactor.finishInteractiveTransition()
} default:
break
}
}
}
import UIKit
class DismissAnimator: NSObject {
}
extension DismissAnimator : UIViewControllerAnimatedTransitioning {
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
return 1.0
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
guard
let fromVC = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey),
let toVC = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey),
let containerView = transitionContext.containerView()
else {
return
}
containerView.insertSubview(toVC.view, belowSubview: fromVC.view)
let screenBounds = UIScreen.mainScreen().bounds
let topLeftCorner = CGPoint(x: 0, y: -screenBounds.height * 2)
let finalFrame = CGRect(origin: topLeftCorner, size: screenBounds.size)
UIView.animateWithDuration(
transitionDuration(transitionContext),animations: {fromVC.view.frame = finalFrame},
completion: { _ in transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
}
)
}
}

Answer 1

If you want a simple Pan Gesture to switch between UIViewControllers, you can check out this:
http://www.appcoda.com/custom-segue-animations/
If you want it to be interactive, as in you can go back and forth between VCs without having to complete the whole transition, I suggest you check out this:
https://www.youtube.com/watch?v=3jAlg5BnYUU
If you want to go even further and have a custom dismissing animation, then look no further than this:
https://www.raywenderlich.com/110536/custom-uiviewcontroller-transitions