IOS 基础之 (二十三) UINavigationController控制器

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
   //创建window
    self.window = [[UIWindow alloc]init];
    
    //给wiindow一个跟控制器
    UINavigationController *nav = [[UINavigationController alloc]init];
    self.window.rootViewController = nav;
    
    //设置主要的并且显示
    [self.window makeKeyAndVisible];
    return YES;
}