iPhone Duo Hinge, Displays and Cameras

Here is a UIKit helper that handles a failed scene request and explains it to the user. It does not assume another window is available on the current display.

Window Request Helper

import UIKit

@MainActor
extension UIViewController {
    func requestNewWindow(for activity: NSUserActivity) {
        UIApplication.shared.requestSceneSessionActivation(
            nil,
            userActivity: activity,
            options: nil
        ) { [weak self] error in
            let details = error.localizedDescription
            Task { @MainActor [weak self] in
                guard let self,
                      self.viewIfLoaded?.window != nil,
                      self.presentedViewController == nil else {
                    return
                }

                let alert = UIAlertController(
                    title: "Cannot Open Another Window",
                    message: "Another window may not be available "
                        + "on this display.\n\n" + details,
                    preferredStyle: .alert
                )
                alert.addAction(UIAlertAction(
                    title: "OK", style: .default
                ))
                self.present(alert, animated: true)
            }
        }
    }
}

Next steps

• Confirm multiple-scene support and handle the supplied activity in the new scene.
• Use UIWindowScene.ActivationAction for an availability-aware menu control.
• Test successful activation on the inner display and failure handling on the outer display.