Custom UIViewController Transition using UIStoryboardSegue

The most popular way is to use UIViewControllerAnimatedTransitioning.

To do this, you must do the following:

• Create a subclass, which can be called “XXXTransitioning”, inheriting from “NSObject” and implementing the two functions in the “UIViewControllerAnimatedTransitioning” protocol.

func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval
func animateTransition(using transitionContext: UIViewControllerContextTransitioning)

• Then:
  1. Create an instance of “XXXTransitioning” in the “ViewController “.
  2. Set transitioningDelegate = self.
  3. Extend “ViewController” with UIViewControllerTransitioningDelegate and implement:

func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning?

dismiss

I noticed that the Storyboard Segue has a Custom option.

class XXXModalSegue: UIStoryboardSegue {
    override func perform() {
        let fromVC = source
        let toVC = destination

        let fromView = fromVC.view!
        let toView  = toVC.view!

        let (w, h) = (UIScreen.main.bounds.width, UIScreen.main.bounds.height)

        toView.alpha = 0
        toView.frame = CGRect(x: w/2, y: 0, width: w, height: h)

        let window = UIApplication.shared.keyWindow
        window?.insertSubview(toView, aboveSubview: fromView)

        UIView.animate(withDuration: 0.4, animations: {
            toView.alpha = 1
            toView.frame = toView.frame.offsetBy(dx: -w/2, dy: 0)
        }) { (b) in

            self.source.present(self.destination, animated: false, completion: nil)
            // OR: self.source.dismiss(animated: false, completion: nil)
        }
    }
}

That’s it, no need for coding delegate and Extension. Simple and clean :)

Translated by gpt-3.5-turbo