iOS11以后新建工程多了两个文件SceneDelegate.h,SceneDelegate.m，以及AppDelegate.m少了不少方法及window，原来新建的窗口导航根控制器肯定是不可行了，那么如何在新建的项目中适用呢
1.不支持多窗口，使用原理的AppDelegate.m，找到info.list 把Application Scene Manifest干掉.
2.AppDelegate添加widow
3.把新增的- (UISceneConfiguration *)application:(UIApplication *)application configurationForConnectingSceneSession:(UISceneSession *)connectingSceneSession options:(UISceneConnectionOptions *)options 和- (void)application:(UIApplication *)application didDiscardSceneSessions:(NSSet<UISceneSession *> *)sceneSessions 方法干掉
4.写上你的代码即可

• (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

if (@available(iOS 13,*)) {
       return YES;
   } else {
       self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
       UINavigationController *rootNavgationController = [[UINavigationController alloc] initWithRootViewController:[ViewController new]];
       self.window.rootViewController = rootNavgationController;
       [self.window makeKeyAndVisible];
       return YES;
   }

}

二 如何支持多窗口SceneDelegate写呢?
1.之前info.list 下的Application Scene Manifest保留
2.在SceneDelegate.m下面写，这是iOS13后的

• (void)scene:(UIScene *)scene willConnectToSession:(UISceneSession *)session options:(UISceneConnectionOptions )connectionOptions {
  self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
  self.window.windowScene = (UIWindowScene)scene;
  UINavigationController *rootNavgationController = [[UINavigationController alloc] initWithRootViewController:[ViewController new]];
  self.window.rootViewController = rootNavgationController;
  [self.window makeKeyAndVisible];
  }
  3.如果要iOS13前的还需要添加
• (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {

if (@available(iOS 13,*)) {
       return YES;
   } else {
       self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
       UINavigationController *rootNavgationController = [[UINavigationController alloc] initWithRootViewController:[ViewController new]];
       self.window.rootViewController = rootNavgationController;
       [self.window makeKeyAndVisible];
       return YES;
   }

}