- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [[UIApplication sharedApplication] setStatusBarHidden:YES];
    self.navigationController.navigationBar.hidden = YES;
    self.tabBarController.tabBar.hidden = YES;
}

- (void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    [[UIApplication sharedApplication] setStatusBarHidden:NO];
    self.navigationController.navigationBar.hidden = NO;
    self.tabBarController.tabBar.hidden = NO;
}

2. 如果是想把整个应用程序的状态栏都隐藏掉，操作如下

在info.plist上添加一项：Status bar is initially hidden，value为YES；

    完后在AppDelegate.m的- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions方法里面加上如下一句就可以了：

    [[UIApplication sharedApplication]setStatusBarHidden:YES withAnimation:UIStatusBarAnimationFade];
、、、