The purpose of this story is to demonstrate the creation of a custom presentation controller.
In my example, there will be a button on first view controller and when user taps on it, the detail view controller will be opened in a custom presentation controller.
Here’s the first view controller:
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| import UIKit | |
| class ViewController: UIViewController { | |
| override func viewDidLoad() { | |
| super.viewDidLoad() | |
| } | |
| @IBAction func buttonTapped(_ sender: UIButton) { | |
| let vc = DetailViewController() | |
| vc.modalPresentationStyle = .custom | |
| vc.transitioningDelegate = self | |
| self.present(vc, animated: true, completion: nil) | |
| } | |
| } | |
| extension ViewController: UIViewControllerTransitioningDelegate { | |
| func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? { | |
| return CustomPresentationController(presentedViewController: presented, presenting: presenting) | |
| } | |
| } |
We need to create our custom presentation controller. Custom presentation controller has a dimming view which covers all the screen. The height of the detail view controller is 2/3 of the presentation controller and its origin y position starts at 1/3 height of the presentation controller. Of course this is just an example, you can change layout however you wish. Here’s the code for the custom presentation controller:
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| import UIKit | |
| final class CustomPresentationController: UIPresentationController { | |
| // MARK: – Properties | |
| private lazy var dimmingView: UIView = { | |
| let dimmingView = UIView() | |
| dimmingView.translatesAutoresizingMaskIntoConstraints = false | |
| dimmingView.backgroundColor = UIColor(white: 0.0, alpha: 0.5) | |
| dimmingView.alpha = 0.0 | |
| let recognizer = UITapGestureRecognizer(target: self, | |
| action: #selector(handleTap(recognizer:))) | |
| dimmingView.addGestureRecognizer(recognizer) | |
| return dimmingView | |
| }() | |
| override var frameOfPresentedViewInContainerView: CGRect { | |
| var frame: CGRect = .zero | |
| frame.size = size(forChildContentContainer: presentedViewController, | |
| withParentContainerSize: containerView!.bounds.size) | |
| frame.origin.y = containerView!.frame.height*(1.0/3.0) | |
| return frame | |
| } | |
| override func presentationTransitionWillBegin() { | |
| guard let containerView = containerView else { | |
| return | |
| } | |
| containerView.insertSubview(dimmingView, at: 0) | |
| NSLayoutConstraint.activate([ | |
| dimmingView.topAnchor.constraint(equalTo: containerView.topAnchor), | |
| dimmingView.leadingAnchor.constraint(equalTo: containerView.leadingAnchor), | |
| dimmingView.trailingAnchor.constraint(equalTo: containerView.trailingAnchor), | |
| dimmingView.bottomAnchor.constraint(equalTo: containerView.bottomAnchor) | |
| ]) | |
| guard let coordinator = presentedViewController.transitionCoordinator else { | |
| dimmingView.alpha = 1.0 | |
| return | |
| } | |
| coordinator.animate(alongsideTransition: { _ in | |
| self.dimmingView.alpha = 1.0 | |
| }) | |
| } | |
| override func dismissalTransitionWillBegin() { | |
| guard let coordinator = presentedViewController.transitionCoordinator else { | |
| dimmingView.alpha = 0.0 | |
| return | |
| } | |
| coordinator.animate(alongsideTransition: { _ in | |
| self.dimmingView.alpha = 0.0 | |
| }) | |
| } | |
| override func containerViewWillLayoutSubviews() { | |
| presentedView?.frame = frameOfPresentedViewInContainerView | |
| } | |
| override func size(forChildContentContainer container: UIContentContainer, | |
| withParentContainerSize parentSize: CGSize) -> CGSize { | |
| return CGSize(width: parentSize.width, height: parentSize.height*(2.0/3.0)) | |
| } | |
| } | |
| // MARK: – Private | |
| private extension CustomPresentationController { | |
| @objc func handleTap(recognizer: UITapGestureRecognizer) { | |
| presentingViewController.dismiss(animated: true) | |
| } | |
| } |
And the result:
iOS Tricks 