“屏幕”的设置在iOS 13.0中已弃用

Question

我试图按照本教程创建多屏应用程序：

https://www.youtube.com/watch?v=UYviLiI2rlY&t=774s

很遗憾，在25:00-26:00时出现错误，并且外部屏幕保持黑屏：

[Assert] Error in UIKit client: -[UIWindow setScreen:] should not be called if the client adopts
UIScene lifecycle. Call -[UIWindow setWindowScene:] instead.

我的代码是：

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var textView: UITextView!
    var additionalWindows = [UIWindow]()

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(forName: UIScreen.didConnectNotification, object: nil, queue: nil) { [weak self] notification in
            guard let self = self else {return}

            guard let newScreen = notification.object as? UIScreen else {return}
            let screenDimensions = newScreen.bounds

            let newWindow = UIWindow(frame: screenDimensions)
            newWindow.screen = newScreen

            guard let vc = self.storyboard?.instantiateViewController(withIdentifier: "PreviewViewController") as? PreviewViewController else {
                fatalError("Unable to find PreviewViewController")
            }

            newWindow.rootViewController = vc
            newWindow.isHidden = false
            self.additionalWindows.append(newWindow)
        }
    }


}

而且我在newWindow.screen = newScreen中有弃用警报：Setter for 'screen' was deprecated in iOS 13.0，但我找不到任何有用的方法，并且在解决此问题方面也没有太复杂。

Answer 1

请注意，您应该按照externalWindow.rootViewController实例化VC

在我的情况下，我使用外部显示器显示custom UIView()，所以我使用空的UIViewController()，然后向其中添加视图。

private func setupExternalScreen(screen: UIScreen, retryUntilSet: Bool = true, retryTimesUntilDiscarded: Int = 0) {
    var matchingWindowScene: UIWindowScene? = nil
    let scenes = UIApplication.shared.connectedScenes
    for item in scenes {
        if let windowScene = item as? UIWindowScene {
            if (windowScene.screen == screen) {
                matchingWindowScene = windowScene
                break
            }
            }
    }
    if matchingWindowScene == nil {
        if true == retryUntilSet {
            DispatchQueue.main.asyncAfter(deadline: .now() + 1) {
                if retryTimesUntilDiscarded < 5 {
                        self.setupExternalScreen(screen:screen, retryUntilSet: false, retryTimesUntilDiscarded += 1)
                } else {
                    let alert = UIAlertController(title: "Not connected", message: "Reconnect the display and try again", preferredStyle: .alert)
                        let ok = UIAlertAction(title: "Ok", style: .default, handler: nil)
                        alert.addAction(ok)
                        self.present(alert, animated: true, completion: nil)
                }
            }
        }
        return
    }
    externalWindow = UIWindow(frame: screen.bounds)
    externalWindow.rootViewController = UIViewController()
    airplayView.frame = externalWindow.frame
    if !externalWindow.subviews.contains(airplayView) {
        externalWindow.rootViewController?.view.addSubview(airplayView)
        if let _ = view.window {
            view.window?.makeKey()
        }
    } else {
        airplayView.updateValues()
    }

    externalWindow.windowScene = matchingWindowScene
    externalWindowWindow.isHidden = false
}

[如果您的应用需要iOS <13，则可能需要使用if #available(iOS 13.0, *) {}决定如何设置外部屏幕。

忘记提及... externalWindow在我需要使用第二个屏幕的ViewController中声明

lazy var externalWindow = UIWindow()