iOS13外屏镜像，得到错误：setScreen不应该被调用。

Question

我正试图在iOS 13中向外部连接的屏幕呈现一个自定义视图控制器。我遵循了这个教程。

http:/www.spazstik-software.comblogarticlehow-to-display-custom-content-on-a-external-screen-from-a-ios-device

我有以下代码。

/// A private method used to setup a external screen with a window
/// loaded with a ExternalScreenViewController
///
/// - parameter screen: A UIScreen object to connect the
/// ExternalScreenViewController too
private func setupExternalScreen(screen: UIScreen) {
  guard externalWindow == nil,
    let vc = self.storyboard?.instantiateViewControllerWithIdentifier("ExternalScreen") as? ExternalScreenViewController else {
      return
  }

  externalWindow = UIWindow(frame: screen.bounds)
  externalWindow!.rootViewController = vc
  externalWindow!.screen = screen
  externalWindow!.hidden = false
}

在这一行 externalWindow!.screen = screen 我在Xcode 11.4.1控制台得到一个错误。

[断言]UIKit客户端中的错误：如果客户端采用UIScene生命周期，则不应调用-[UIWindow setScreen:]。调用-[UIWindow setWindowScene:]代替。

自定义视图控制器不显示在外部显示中。

我应该怎么改？我想同时处理iOS 13.x和以前的设备。

Answer 1

在iOS 13设备中，没有设置 screen，你应该设置 windowScene 在...上 externalWindow 对象。在这之前，你应该找出匹配的 windowScene 从 UIApplication的连接场景。修改后的方法如下。

private func setupExternalScreen(screen: UIScreen, shouldRecurse: Bool = true) {
    // For iOS13 find matching UIWindowScene
    var matchingWindowScene: UIWindowScene? = nil
    if #available(iOS 13.0, *) {
        let scenes = UIApplication.shared.connectedScenes
        for aScene in scenes {
            if let windowScene = aScene as? UIWindowScene {
                // Look for UIWindowScene that has matching screen
                if (windowScene.screen == screen) {
                    matchingWindowScene = windowScene
                    break
                }
            }
        }
        if matchingWindowScene == nil {
            // UIWindowScene has not been created by iOS rendered yet
            // Lets recall self after delay of two seconds
            if true == shouldRecurse {
                DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 2) {
                    self.setupExternalScreen(screen:screen, shouldRecurse: false)
                }
            }
            // Dont proceed furthure in iOS13
            return
        }
    }

    guard externalWindow == nil, let vc = self.storyboard?.instantiateViewControllerWithIdentifier("ExternalScreen") as? ExternalScreenViewController else {
      return
    }

    externalWindow = UIWindow(frame: screen.bounds)
    externalWindow!.rootViewController = vc
    if #available(iOS 13.0, *) {
        // Set windowScene here, no need to set screen
        externalWindow!.windowScene = matchingWindowScene
    } else {
        // Set screen the traditional way
        externalWindow!.screen = screen
    }
    externalWindow!.isHidden = false

}

注意： 我们应该设置 isHidden 作为 hidden 已被废弃。