Black Screen with UIViewControllerAnimatedTransitioning - ios

Question

I have created a transition and it is working fine except that I get sometime black corners in the simulator. Additionally in iPad Pro I get a completely black screen if I run the simulator in full resolution. The resized resolutions work fine. Do you have an idea what might be the problem?
Another thing that I recognized is that the content behind the black screen is there and responds to touches. E.g. on a touch I reload the cell of a collectionview. Then this cell is visible while the rest of the collectionview is black.
class ZoomInCircleViewTransition: NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate {
var transitionContext: UIViewControllerContextTransitioning?
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
return 0.6
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
self.transitionContext = transitionContext
guard let toViewController: UIViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey) else {
return
}
guard let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey) else { return
}
guard let fromViewTransitionFromView = fromViewController as? TransitionFromViewProtocol else {
return
}
let imageViewSnapshot = fromViewTransitionFromView.getViewForTransition()
let endFrame = CGRectMake(-CGRectGetWidth(toViewController.view.frame)/2, -CGRectGetHeight(toViewController.view.frame)/2, CGRectGetWidth(toViewController.view.frame)*2, CGRectGetHeight(toViewController.view.frame)*2)
if let containerView = transitionContext.containerView(){
containerView.addSubview(fromViewController.view)
containerView.addSubview(toViewController.view)
containerView.addSubview(imageViewSnapshot)
}
let maskPath = UIBezierPath(ovalInRect: imageViewSnapshot.frame)
let maskLayer = CAShapeLayer()
maskLayer.frame = toViewController.view.frame
maskLayer.path = maskPath.CGPath
toViewController.view.layer.mask = maskLayer
let quadraticEndFrame = CGRect(x: endFrame.origin.x - (endFrame.height - endFrame.width)/2, y: endFrame.origin.y, width: endFrame.height, height: endFrame.height)
let bigCirclePath = UIBezierPath(ovalInRect: quadraticEndFrame)
let pathAnimation = CABasicAnimation(keyPath: "path")
pathAnimation.delegate = self
pathAnimation.fromValue = maskPath.CGPath
pathAnimation.toValue = bigCirclePath
pathAnimation.duration = transitionDuration(transitionContext)
maskLayer.path = bigCirclePath.CGPath
maskLayer.addAnimation(pathAnimation, forKey: "pathAnimation")
let hideImageViewAnimation = {
imageViewSnapshot.alpha = 0.0
}
UIView.animateWithDuration(0.2, delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: hideImageViewAnimation) { (completed) -> Void in
}
let scaleImageViewAnimation = {
imageViewSnapshot.frame = quadraticEndFrame
}
UIView.animateWithDuration(transitionDuration(transitionContext), delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: scaleImageViewAnimation) { (completed) -> Void in
// After the complete animations hav endet
imageViewSnapshot.removeFromSuperview()
}
}
override func animationDidStop(anim: CAAnimation, finished flag: Bool) {
if let transitionContext = self.transitionContext {
transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
}
}
// MARK: UIViewControllerTransitioningDelegate protocol methods
// return the animataor when presenting a viewcontroller
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
// return the animator used when dismissing from a viewcontroller
func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
}

Answer 1

You need remove mask layer once your are done with custom transition animations.
toViewController.view.layer.mask = nil
Please use this updated code:
class ZoomInCircleViewTransition: NSObject, UIViewControllerAnimatedTransitioning, UIViewControllerTransitioningDelegate {
var transitionContext: UIViewControllerContextTransitioning?
func transitionDuration(transitionContext: UIViewControllerContextTransitioning?) -> NSTimeInterval {
return 0.6
}
func animateTransition(transitionContext: UIViewControllerContextTransitioning) {
self.transitionContext = transitionContext
guard let toViewController: UIViewController = transitionContext.viewControllerForKey(UITransitionContextToViewControllerKey) else {
return
}
guard let fromViewController = transitionContext.viewControllerForKey(UITransitionContextFromViewControllerKey) else { return
}
guard let fromViewTransitionFromView = fromViewController as? TransitionFromViewProtocol else {
return
}
let imageViewSnapshot = fromViewTransitionFromView.getViewForTransition()
let endFrame = CGRectMake(-CGRectGetWidth(toViewController.view.frame)/2, -CGRectGetHeight(toViewController.view.frame)/2, CGRectGetWidth(toViewController.view.frame)*2, CGRectGetHeight(toViewController.view.frame)*2)
if let containerView = transitionContext.containerView(){
containerView.addSubview(fromViewController.view)
containerView.addSubview(toViewController.view)
containerView.addSubview(imageViewSnapshot)
}
let maskPath = UIBezierPath(ovalInRect: imageViewSnapshot.frame)
let maskLayer = CAShapeLayer()
maskLayer.frame = toViewController.view.frame
maskLayer.path = maskPath.CGPath
toViewController.view.layer.mask = maskLayer
let quadraticEndFrame = CGRect(x: endFrame.origin.x - (endFrame.height - endFrame.width)/2, y: endFrame.origin.y, width: endFrame.height, height: endFrame.height)
let bigCirclePath = UIBezierPath(ovalInRect: quadraticEndFrame)
let pathAnimation = CABasicAnimation(keyPath: "path")
pathAnimation.delegate = self
pathAnimation.fromValue = maskPath.CGPath
pathAnimation.toValue = bigCirclePath
pathAnimation.duration = transitionDuration(transitionContext)
maskLayer.path = bigCirclePath.CGPath
maskLayer.addAnimation(pathAnimation, forKey: "pathAnimation")
let hideImageViewAnimation = {
imageViewSnapshot.alpha = 0.0
}
UIView.animateWithDuration(0.2, delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: hideImageViewAnimation) { (completed) -> Void in
}
let scaleImageViewAnimation = {
imageViewSnapshot.frame = quadraticEndFrame
}
UIView.animateWithDuration(transitionDuration(transitionContext), delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: scaleImageViewAnimation) { (completed) -> Void in
// After the complete animations hav endet
imageViewSnapshot.removeFromSuperview()
toViewController.view.layer.mask = nil
}
}
override func animationDidStop(anim: CAAnimation, finished flag: Bool) {
if let transitionContext = self.transitionContext {
transitionContext.completeTransition(!transitionContext.transitionWasCancelled())
}
}
// MARK: UIViewControllerTransitioningDelegate protocol methods
// return the animataor when presenting a viewcontroller
func animationControllerForPresentedController(presented: UIViewController, presentingController presenting: UIViewController, sourceController source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
// return the animator used when dismissing from a viewcontroller
func animationControllerForDismissedController(dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return self
}
}

Answer 2

In my case, I had set the presentation style and delegate in the incorrect place. When placed in viewDidLoad(), the transitioningDelegate is honored, but the modalPresentationStyle is not — resulting in a black screen. I had to move the style to be set earlier on init.
class MyViewController: UIViewController {
init() {
super.init(nibName: String(describing: type(of: self)), bundle: .main)
transitioningDelegate = self
modalPresentationStyle = .custom
}
#available(*, unavailable)
required init?(coder aDecoder: NSCoder) {
fatalError()
}
override func viewDidLoad() {
super.viewDidLoad()
// I incorrectly had the delegate and presentationStyle set here.
}
}
extension MyViewController: UIViewControllerTransitioningDelegate {
//...
}
Calling class:
let vc = MyViewController()
present(vc, animated: true)