Disable the interactive dismissal of presented view controller

1. If you want the same behaviour as it's in previous iOS version (< iOS13) like model presentation in fullscreen, just set the presentation style of your destination view controller to UIModalPresentationStyle.fullScreen

   let someViewController = \*VIEW CONTROLLER*\
   someViewController.modalPresentationStyle = .fullScreen
   

   And if you are using storyboard just select the segua and select Full Screen form the Presentation dropdown.

   

2. If you just want to disable the interactive dismissal and keep the new presentation style set UIViewController property isModalInPresentation to true.

   if #available(iOS 13.0, *) {
       someViewController.isModalInPresentation = true // available in IOS13
   }
   

If you have some business logic, something like all fields should be filled before dismissing, you should:

On ViewDidLoad if your ViewController has been presented within a Navigation Controller:

func viewDidLoad() { 
    self.navigationController?.presentationController?.delegate = self
}

If not, simply use

func viewDidLoad() { 
    self.presentationController?.delegate = self
}

Then implement the delegate method:

extension ViewController: UIAdaptivePresentationControllerDelegate {

    func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {
        guard let text = firstName.text, text.isEmpty else { return false }
        guard let text = lastName.text, text.isEmpty else { return false }
        ...
    
        return true
    }

}

Option 1:

viewController.isModalInPresentation = true

(Disabled interactive .pageSheet dismissal acts like this.)

• Since the iOS 13, UIViewController contains a new property called isModalInPresentation which must be set to true to prevent the interactive dismissal.
• It basically ignores events outside the view controller's bounds. Bear that in mind if you are using not only the automatic style but also presentation styles like .popover etc.
• This property is false by default.

From the official docs: If true, UIKit ignores events outside the view controller's bounds and prevents the interactive dismissal of the view controller while it is onscreen.

---

Option 2:

func presentationControllerShouldDismiss(_ presentationController: UIPresentationController) -> Bool {
    return false
}

• Since the iOS 13, UIAdaptivePresentationControllerDelegate contains a new method called presentationControllerShouldDismiss.
• This method is called only if the presented view controller is not dismissed programmatically and its isModalInPresentation property is set to false.

Tip: Don't forget to assign presentationController's delegate. But be aware, it is known that even just accessing the presentationController can cause a memory leak.

The property isModalInPresentation might help.

From the documentation:

When you set it to true, UIKit ignores events outside the view controller's bounds and prevents the interactive dismissal of the view controller while it is onscreen.

You can use it like this:

let controller = MyViewController()
controller.isModalInPresentation = true
self.present(controller, animated: true, completion: nil)