UIApplicationDelegate

为了支持scene，在UIApplicationDelegate方法中增加了，下面方法

核心实现方法

- (UISceneConfiguration *)application:(UIApplication *)application configurationForConnectingSceneSession:(UISceneSession *)connectingSceneSession options:(UISceneConnectionOptions *)options  API_AVAILABLE(ios(13.0)){
    // Called when a new scene session is being created.
    // Use this method to select a configuration to create the new scene with.
    return [[UISceneConfiguration alloc] initWithName:@"Default Configuration" sessionRole:connectingSceneSession.role];
}


- (void)application:(UIApplication *)application didDiscardSceneSessions:(NSSet<UISceneSession *> *)sceneSessions  API_AVAILABLE(ios(13.0)){
    // 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.
}

configurationForConnectingSceneSession

需要通过这个方法去info.plist中读取scene信息，创建新的scene

scene代理

一个实现UIWindowSceneDelegate的类，继承自
UIResponder

@interface SceneDelegate : UIResponder <UIWindowSceneDelegate>

@property (strong, nonatomic) UIWindow * window;

@end

对于Application Session Role的scene，需要创建root window。如果已经在Info.plist中的Scene Configuration指定了Storyboard Name，那么root window会自动从Storyboard中创建。如果没有指定Storyboard Name，那么就需要在-[UIWindowSceneDelegate scene:willConnectToSession:options:]中手动创建root window。

- (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions *)connectionOptions  API_AVAILABLE(ios(13.0)){
    // 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).
          UIWindowScene *windowScene = (UIWindowScene *)scene;
          self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
          self.window = [[UIWindow alloc] initWithWindowScene:windowScene];
          [self.window setWindowScene:windowScene];
          [self.window setBackgroundColor:[UIColor whiteColor]];
          [self setsViewController];
    //          [self.window setRootViewController:[UITabBarController new]];
          
          [self.window makeKeyAndVisible];
}