iOS 隐藏下级页面的tabbar的统一处理

在自己的navigationController中重写push方法可以统一对下级页面做处理。

// 拦截
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated{
    if (self.viewControllers.count > ) {
        viewController.hidesBottomBarWhenPushed = YES;
        viewController.navigationItem.leftBarButtonItem = 
        [[UIBarButtonItem alloc] initWithImage:[UIImage imageNamed:@"IMAGENAME"] 
        style:UIBarButtonItemStylePlain target:self action:@selector(back)];//统一设置左上角返回键
    }
    [super pushViewController:viewController animated:animated];
}
- (void)back{
    [self popViewControllerAnimated:YES];
}