从iOS 11+项目中删除SceneDelegate的正确方法-应用程序中需要哪些代码(_：didFinishLaunchingWithOptions)

Question

在Xcode12中创建新的iOS项目时，会自动添加一个UISceneDelegate。由于我的应用程序应该在iOS 11+ (不支持UISceneDelegate)上可用，所以我不得不删除它。

当然，从info.plist和AppDelegate中删除UISceneDelegate是没有问题的。然而，我想知道我是否必须向application(_: didFinishLaunchingWithOptions)添加任何代码在大多数教程中，我发现这个方法只是留空了，只需要添加var window: UIWindow?。其他来源显示，必须添加一些设置代码。

class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    
        /* Manual Setup */
        // let window = UIWindow(frame: UIScreen.main.bounds)    
        // window.rootViewController = ViewController() // Your initial view controller.
        // window.makeKeyAndVisible()
        // self.window = window

        return true
    }
} 

在我的测试中，没有任何额外的设置代码，一切都运行得很好。rootViewController是从故事板自动加载的，一切工作正常。

这是巧合吗?这是在后台发生的一些Xcode魔术(如果缺少代码，会自动添加rootVC )，还是我的代码(没有设置)损坏了，最终会在某个非常糟糕的时刻失败

Answer 1

你只需要确保

1-删除UISceneDelegate

2-从Info.plist中删除密钥

3-这些方法从AppDelegate中删除

// MARK: UISceneSession Lifecycle

func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
    // Called when a new scene session is being created.
    // Use this method to select a configuration to create the new scene with.
    return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
}

func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
    // Called when the user discards a scene session.
    // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
    // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
}

4-向AppDelegate添加var window: UIWindow?

5-确保在Main.storyboard中选择了入口点vc

在此之后，不要担心任何事情，并保留didFinishLaunchingWithOptions为空，就像Xcode 11中没有发生任何更改一样