This is a delegate you can create that can do some additional processing between UIViewController transitions when using 'viewController.present'.
By defining a delegate
import UIKit
class CustomTransitionDelegate: NSObject, UIViewControllerTransitioningDelegate {
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return FadePushAnimator()
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return FadePopAnimator()
}
}And then setting it on the viewController you are transitioning too...
@objc func buttonPressed() {
let vc2 = ViewController2()
vc2.transitioningDelegate = transitionDelegate
present(vc2, animated: true, completion: nil)
}You can add animations and customize transitions from one viewController to another.
import UIKit
class ViewController1: UIViewController {
let transitionDelegate: UIViewControllerTransitioningDelegate = CustomTransitionDelegate()
override func viewDidLoad() {
super.viewDidLoad()
setupViews()
}
func setupViews() {
view.backgroundColor = .red
let button = makeButton(title: "Go to Next")
button.addTarget(self, action: #selector(buttonPressed), for: .touchUpInside)
view.addSubview(button)
view.centerXAnchor.constraint(equalTo: button.centerXAnchor).isActive = true
view.centerYAnchor.constraint(equalTo: button.centerYAnchor).isActive = true
}
@objc func buttonPressed() {
let vc2 = ViewController2()
vc2.transitioningDelegate = transitionDelegate
present(vc2, animated: true, completion: nil)
}
}
extension UIViewController {
func makeButton(title: String) -> UIButton {
let button = UIButton()
button.translatesAutoresizingMaskIntoConstraints = false
button.setTitle(title, for: .normal)
button.setTitleColor(.black, for: .normal)
button.contentEdgeInsets = UIEdgeInsets.init(top: 8, left: 16, bottom: 8, right: 16)
return button
}
}import UIKit
class ViewController2: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
setupViews()
}
func setupViews() {
view.backgroundColor = .blue
let button = makeButton(title: "Go back")
button.addTarget(self, action: #selector(button2Pressed), for: .touchUpInside)
view.addSubview(button)
view.centerXAnchor.constraint(equalTo: button.centerXAnchor).isActive = true
view.centerYAnchor.constraint(equalTo: button.centerYAnchor).isActive = true
}
@objc func button2Pressed() {
dismiss(animated: true)
}
}import UIKit
class CustomTransitionDelegate: NSObject, UIViewControllerTransitioningDelegate {
func animationController(forPresented presented: UIViewController, presenting: UIViewController, source: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return FadePushAnimator()
}
func animationController(forDismissed dismissed: UIViewController) -> UIViewControllerAnimatedTransitioning? {
return FadePopAnimator()
}
}import UIKit
class FadePushAnimator: NSObject, UIViewControllerAnimatedTransitioning {
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.5
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
guard
let toViewController = transitionContext.viewController(forKey: .to)
else {
return
}
transitionContext.containerView.addSubview(toViewController.view)
toViewController.view.alpha = 0
let duration = self.transitionDuration(using: transitionContext)
UIView.animate(withDuration: duration, animations: {
toViewController.view.alpha = 1
}, completion: { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
})
}
}import UIKit
class FadePopAnimator: NSObject, UIViewControllerAnimatedTransitioning {
func transitionDuration(using transitionContext: UIViewControllerContextTransitioning?) -> TimeInterval {
return 0.5
}
func animateTransition(using transitionContext: UIViewControllerContextTransitioning) {
guard
let fromViewController = transitionContext.viewController(forKey: .from),
let toViewController = transitionContext.viewController(forKey: .to)
else {
return
}
transitionContext.containerView.insertSubview(toViewController.view, belowSubview: fromViewController.view)
let duration = self.transitionDuration(using: transitionContext)
UIView.animate(withDuration: duration, animations: {
fromViewController.view.alpha = 0
}, completion: { _ in
transitionContext.completeTransition(!transitionContext.transitionWasCancelled)
})
}
}More Links