swift – iOS 26.1: Modal swipe-to-dismiss freezes on iPhone 14 Pro Max / iPhone 17 / iPhone 17 Pro Max but works on iPhone 11 / iPhone 16e

.pageSheet interactive swipe-to-dismiss freezes when UIDesignRequiresCompatibility = YES on specific iPhone models (iOS 26.x)

Area

UIKit → View Controller Presentation

Type of Issue

Serious Bug (App Freeze / UI Hang)

Description

Interactive dismissal of a modal view controller using .pageSheet freezes mid-gesture on specific iPhone models when UIDesignRequiresCompatibility is enabled.

The freeze occurs during the swipe-to-dismiss gesture, before dismissal completes. UIKit lifecycle callbacks never finish (viewDidDisappear is not called), and the app becomes completely unresponsive.

This issue appears to be device-specific and project-specific, and does not reproduce in a fresh project with the same code.

Steps to Reproduce

1. Create an iOS app with deployment target iOS 13.0

2. In Info.plist, set:

   UIDesignRequiresCompatibility = YES
   
   

3. Present a modal view controller using .pageSheet

4. Swipe down to dismiss the modal

5. Observe freeze mid-gesture (~20% progress)

Expected Results

Actual Results

• App freezes mid-dismissal gesture

• UI becomes unresponsive

• No crash or console error

• viewDidDisappear is never called

Minimal Code Sample

class TestModalViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemBackground
    }
}

let modal = TestModalViewController()
modal.modalPresentationStyle = .pageSheet
present(modal, animated: true)

Regression

• ❌ Does NOT occur when UIDesignRequiresCompatibility = NO

• ❌ Does NOT occur with .fullScreen

• ❌ Does NOT occur in a fresh test project

• ✅ Occurs consistently in existing project

Devices Tested

Affected

• iPhone 14 Pro Max

• iPhone 17

• iPhone 17 Pro Max

Not Affected

iOS Versions

Notes

• Issue occurs during UIKit’s interactive dismissal animation

• No custom transitions or animations

• Programmatic dismissal works

• Appears related to compatibility layout / gesture handling on large-screen devices