应用第一次启动，修改rootViewController方法

1、第一次设置

        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        NewEntryController *controller = [[NewEntryController alloc] initWithNibName:@"NewEntryController" bundle:nil];
        self.window.rootViewController = [[GKNavigationController alloc] initWithRootViewController:controller];
        [self.window makeKeyAndVisible];
        return;

2、修改rootViewController

    
    AppDelegate *delegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    // 在delegate中初始化新的controller
    [delegate initTabbarController];
    // 修改rootViewController
    [delegate.window addSubview:delegate.tabbarController.view];
    [self.view removeFromSuperview];    
    delegate.window.rootViewController = delegate.tabbarController;