Implementing a Custom Transition Animation Between View Controllers in Swift 5.5 Results in Inconsistent Behavior
I'm learning this framework and I'm stuck trying to I'm trying to figure out I'm building a feature where I've been struggling with this for a few days now and could really use some help. I'm currently developing an iOS app using Swift 5.5 and I've been trying to implement a custom transition animation between two view controllers. The transition works as expected in most cases, but I’m experiencing inconsistent behavior when transitioning from the main view controller to a detail view controller. Sometimes, the animation stutters or doesn’t complete properly, resulting in the detail view controller appearing abruptly without the desired fade effect. I’ve defined a custom transition delegate and used the `UIViewControllerAnimatedTransitioning` protocol to manage the animation. Below is the relevant code: ```swift class CustomTransitionAnimator: NSObject, UIViewControllerAnimatedTransitioning { func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval { return 0.5 } func animateTransition(using transitionContext: UIViewControllerContextTransitioning) { guard let fromView = transitionContext.view(forKey: .from), let toView = transitionContext.view(forKey: .to) else { return } let containerView = transitionContext.containerView containerView.addSubview(toView) toView.alpha = 0 UIView.animate(withDuration: transitionDuration(using: transitionContext), animations: { fromView.alpha = 0 toView.alpha = 1 }) { finished in fromView.alpha = 1 transitionContext.completeTransition(!transitionContext.transitionWasCancelled) } } } ``` I've set this animator in the `prepare(for:sender:)` method of my main view controller: ```swift override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if let destination = segue.destination as? DetailViewController { destination.transitioningDelegate = self } } ``` And here’s the implementation for `UIViewControllerTransitioningDelegate`: ```swift extension MainViewController: UIViewControllerTransitioningDelegate { func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? { return CustomTransitionAnimator() } func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? { return CustomTransitionAnimator() } } ``` I’ve tried calling `transitionContext.completeTransition(true)` immediately after `UIView.animate` finishes, but it didn’t help. Additionally, I have checked for any potential layout or view hierarchy issues, but everything seems correct. The issue appears especially on older devices, and I suspect it might have something to do with how the view hierarchy is managed or how the animations are queued. Does anyone have any insight into why the transition might not be performing consistently? Any debugging tips or best practices for custom transitions would be greatly appreciated! What am I doing wrong? I've been using Swift for about a year now. What's the correct way to implement this? The project is a desktop app built with Swift. Any pointers in the right direction? Any advice would be much appreciated.