Xcode11 iOS13 新建Swift项目（黑屏）

不使用StoryBoard加载Main

 info.plist文件中 删除键值对

 StoryBoardName : Main

第一步：AppDelegate添加window，用于 iOS 13 以下加载rootViewController

var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        
        // iOS 13 以下加载rootViewController
        if #available(iOS 13.0, *)  {
           
         } else {
            self.window = UIWindow(frame: UIScreen.main.bounds)
            
             let webVC = LFWebVC()
            self.window?.rootViewController = webVC
            
            let urlString = "https://www.baidu.com/"
            let url = URL.init(string: urlString)
            webVC.openURL(url: url!)
            
            self.window?.makeKeyAndVisible()

         }
        return true
    }

第二步：SceneDelegate用于 iOS 13加载rootViewController

var window: UIWindow?
    
    @available(iOS 13.0, *)
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        //guard let _ = (scene as? UIWindowScene) else { return }
        
        // iOS 13加载rootViewController
        if #available(iOS 13.0, *)  {
            self.window = UIWindow(windowScene: scene as! UIWindowScene)
        } else {
            self.window = UIWindow(frame: UIScreen.main.bounds)
        }
        
       
        self.window?.backgroundColor =  UIColor.red
        
        let webVC = LFWebVC()
        self.window?.rootViewController = webVC
        self.window?.makeKeyAndVisible()
        
        let urlString = "https://www.baidu.com/"
        guard let url = URL.init(string: urlString) else { return }
        webVC.openURL(url: url)
        
    }

第三步：scene相关方法里加上@available(iOS 13.0, *)

    @available(iOS 13.0, *)
    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
    }

    @available(iOS 13.0, *)
    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
    }

    @available(iOS 13.0, *)
    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }

    @available(iOS 13.0, *)
    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }

以上设置完毕即可运行iOS13及其以下系统