创建导航控制器的BarButtonItem

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

    // 创建窗口

    self.window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];

    [self.window setBackgroundColor:[UIColor whiteColor]];

    

    // 创建UINavigationController的子控制器

    UIViewController *viewC = [[UIViewController alloc] init];

    

    // 创建导航控制器并初始化器跟控制器

    UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:viewC];

    

    UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithTitle:@"112233" style:UIBarButtonItemStylePlain target:self action:@selector(click)];

    [barButton setTintColor:[UIColor redColor]];



    // 设置窗口的跟控制器为导航控制器

    self.window.rootViewController = nav;

    viewC.navigationItem.leftBarButtonItem = barButton;

    // 设置窗口为主窗口

    [self.window makeKeyAndVisible];

    

    return YES;

}