swift - 为什么在 xcode 中构建时应用程序变黑了？试图保持用户登录

Question

我试图保持用户登录，所以我写了这段代码：

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
    // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
    // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
    let window = UIWindow(windowScene: scene as! UIWindowScene)
        // Assign window to SceneDelegate window property
        self.window = window
        
        if let loggedIn = UserDefaults.standard.bool(forKey: "IsUserLoggedIn") as? Bool{
            if loggedIn{
                //set your login viewcontroller as root viewcontroller
                let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                let initialViewController = mainStoryBoard.instantiateViewController(withIdentifier: "MainViewController")
                                    self.window?.rootViewController = initialViewController
            }else{
                //open the home screen
                let mainStoryBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                let initialViewController = mainStoryBoard.instantiateViewController(withIdentifier: "TabBarController")
                                    self.window?.rootViewController = initialViewController
                             }
        self.window?.makeKeyAndVisible()
  
        guard let _ = (scene as? UIWindowScene) else { return }   
}
}

它工作正常，但是现在当我构建时，我只得到一个黑屏，并显示以下错误消息：

true
2020-10-20 20:51:14.189415-0400 SimpleProject[80132:3661837] 6.31.0 - [Firebase/Analytics][I-ACS023007] Analytics v.60800000 started
2020-10-20 20:51:14.191734-0400 SimpleProject[80132:3661755] [Firebase/Crashlytics] Version 4.5.0
2020-10-20 20:51:14.189967-0400 SimpleProject[80132:3661837] 6.31.0 - [Firebase/Analytics][I-ACS023008] To enable debug logging set the following application argument: -FIRAnalyticsDebugEnabled 
2020-10-20 20:51:14.205520-0400 SimpleProject[80132:3661836] 6.31.0 - [Firebase/Analytics][I-ACS031025] Analytics screen reporting is enabled. Call +[FIRAnalytics logEventWithName:FIREventScreenView parameters:] to log a screen view event. To disable automatic screen reporting, set the flag FirebaseScreenReportingEnabled to NO (boolean) in the Info.plist
2020-10-20 20:51:14.249061-0400 SimpleProject[80132:3661864] [] nw_protocol_get_quic_image_block_invoke dlopen libquic failed
2020-10-20 20:51:14.291600-0400 SimpleProject[80132:3661755] [Presentation] Presenting view controller <SimpleProject.MainViewController: 0x7f91acb232f0> from detached view controller <SimpleProject.HomeViewController: 0x7f91ab712560> is discouraged.
2020-10-20 20:51:14.341389-0400 SimpleProject[80132:3661755] Unbalanced calls to begin/end appearance transitions for <SimpleProject.TabBarController: 0x7f91ae040a00>.
2020-10-20 20:51:14.343040-0400 SimpleProject[80132:3661834] 6.31.0 - [Firebase/Analytics][I-ACS800023] No pending snapshot to activate. SDK name: app_measurement
2020-10-20 20:51:14.374641-0400 SimpleProject[80132:3661834] 6.31.0 - [Firebase/Crashlytics][I-CLS000000] Failed to download settings Error Domain=FIRCLSNetworkError Code=-5 "(null)" UserInfo={status_code=404, type=2, request_id=, content_type=text/html; charset=utf-8}
2020-10-20 20:51:14.386999-0400 SimpleProject[80132:3661833] 6.31.0 - [Firebase/Analytics][I-ACS800023] No pending snapshot to activate. SDK name: app_measurement
2020-10-20 20:51:14.393543-0400 SimpleProject[80132:3661834] 6.31.0 - [Firebase/Analytics][I-ACS023012] Analytics collection enabled

标签： swiftxcode