- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions  
    {  
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];  
              
        if ([[NSUserDefaults standardUserDefaults] boolForKey:@"firstLaunch"]) {  
            //第一次启动导航页  
            NSLog(@"wanggsx:第一次启动");  
            ViewController *appStartController = [[ViewController alloc] init];  
            self.window.rootViewController = appStartController;  
            [self.window addSubview:appStartController.view];  
        }  
        else  
        {  
            //打开选择场地界面  
            [self switchRootViewController];  
        }  
        [self.window makeKeyAndVisible];  
        return YES;  
    }  
      
    //切换RootViewController  
    - (void)switchRootViewController  
    {  
        self.window.rootViewController = nil;  
        ChooseModeViewController* crBrandsViewController= [[ChooseModeViewController alloc] init];  
        UINavigationController *brandsNavigationController = [self customControllerWithRootViewController:crBrandsViewController];  
        self.viewController = brandsNavigationController;  
        self.window.rootViewController = self.viewController;  
    }  

        - (IBAction)gotoMainView:(id)sender {  
            [[NSUserDefaults standardUserDefaults] setBool:NO forKey:@"firstLaunch"];  
            [(AppDelegate*)[UIApplication sharedApplication].delegate switchRootViewController];  
        }