Dfyjkt

I’m trying to create a custom, short menu that slides up from the bottom of the screen and stays at the bottom (like the iOS share sheet). I’m having a hard time trying to figure out how to do it. I tried presenting a view controller as a modal and setting the preferred content size, but it still presents it as full screen. How can I present a short, modal-like overlay?

You could use a UIPresentationController and a UIViewControllerTransitioningDelegate.

As a starting point here a few lines of code:

UIViewControllerTransitioningDelegate

class OverlayTransitioningDelegate: NSObject, UIViewControllerTransitioningDelegate 

 func presentationController(forPresented presented: UIViewController, presenting: UIViewController?, source: UIViewController) -> UIPresentationController? 
 return OverlayPresentationController(presentedViewController:presented, presenting:presenting)
 

UIPresentationController

class OverlayPresentationController: UIPresentationController 

 private let dimmedBackgroundView = UIView()
 private let height: CGFloat = 200.0

 override init(presentedViewController: UIViewController, presenting presentingViewController: UIViewController?) 
 super.init(presentedViewController: presentedViewController, presenting: presentingViewController)
 let tapGestureRecognizer = UITapGestureRecognizer(target: self, action: #selector(backgroundTapped))
 self.dimmedBackgroundView.addGestureRecognizer(tapGestureRecognizer)
 

 override var frameOfPresentedViewInContainerView: CGRect 
 var frame = CGRect.zero
 if let containerBounds = containerView?.bounds 
 frame = CGRect(x: 0,
 y: containerBounds.height - height,
 width: containerBounds.width,
 height: height)
 
 return frame
 

 override func presentationTransitionWillBegin() 
 if let containerView = self.containerView, let coordinator = presentingViewController.transitionCoordinator 
 containerView.addSubview(self.dimmedBackgroundView)
 self.dimmedBackgroundView.backgroundColor = .black
 self.dimmedBackgroundView.frame = containerView.bounds
 self.dimmedBackgroundView.alpha = 0
 coordinator.animate(alongsideTransition: _ in
 self.dimmedBackgroundView.alpha = 0.5
 , completion: nil)
 
 

 override func dismissalTransitionDidEnd(_ completed: Bool) 
 self.dimmedBackgroundView.removeFromSuperview()
 

 @objc private func backgroundTapped() 
 self.presentedViewController.dismiss(animated: true, completion: nil)
 

How to call it

let overlayTransitioningDelegate = OverlayTransitioningDelegate()

@IBAction func onOpenModalOverlay(_ sender: Any) 
 let overlayVC = OverlayViewController()
 overlayVC.transitioningDelegate = self.overlayTransitioningDelegate
 overlayVC.modalPresentationStyle = .custom
 self.present(overlayVC, animated: true, completion: nil)

Demo

The OverlayViewController is a normal ViewController. Here I used an ugly green background color to make it easier to recognize the overlay.