hidesBottombarWhenPushed的隐藏与显示问题

http://stackoverflow.com/questions/5272290/how-to-hide-uitabbarcontroller

在UITabbarController包含的UINavigationController应用中，如果UINavigationController某一页（某个level）需要隐藏Tabbar，之前的做法是在push那一页之前，将那一页的ViewController中的hidesBottombarWhenPushed参数设为YES，这样当那一页push进UINavigationController中时，底部的Tabbar就会隐藏掉。

但是这种方法有一个潜在的而又巨大的问题，假设现在我有3个ViewController A,B,C，其中为Navigation的RootViewController，A中push B，B中push C。这时，如果我想要在B中隐藏Tabbar，而在C中显示Tabbar，根据最朴素的想法就是：

 

//SecondLevel即为B，此代码在A中进行
SecondLevelViewController *_2vc = [[SecondLevelViewController alloc]initWithNibName:@ "SecondLevelViewController" bundle: nil ];
    _2vc.hidesBottomBarWhenPushed = YES ;
    [ self .navigationController pushViewController:_2vc animated: YES ];

//ThirdLevel即为C，此代码在B中进行
ThirdLevelViewController *_3vc = [[ThirdLevelViewController alloc]initWithNibName:@ "ThirdLevelViewController" bundle: nil ];
    _3vc.hidesBottomBarWhenPushed = NO ;
    [ self .navigationController pushViewController:_3vc animated: YES ];

然而很可惜，虽然A中push B能让Tabbar隐藏，但是B中push C，就没办法让Tabbar显示出来了。这是一个比较郁闷的问题，我只能猜想其中的原理是，当设置某一层hidesBottomBarWhenPushed = YES之后，UITabbarController就像不存在一样，就连调用self.tabbarController或者self.navigationController.tabbarController也应该是nil。

所以解决办法只能是手动隐藏Tabbar。

在B中，加入以下代码：

 

- ( void ) hideTabBar:(UITabBarController *) tabbarcontroller {
    [UIView beginAnimations: nil context: NULL ];
    [UIView setAnimationDuration:0.5];
    for (UIView *view in tabbarcontroller.view.subviews)
    {
        if ([view isKindOfClass:[UITabBar class ]])
        {
            [view setFrame:CGRectMake(view.frame.origin.x, 480, view.frame.size.width, view.frame.size.height)];
        }
        else
        {
            [view setFrame:CGRectMake(view.frame.origin.x, view.frame.origin.y, view.frame.size.width, 480)];
        }
    }
    [UIView commitAnimations];
}

- ( void ) showTabBar:(UITabBarController *) tabbarcontroller {

    [UIView beginAnimations: nil context: NULL ];
    [UIView setAnimationDuration:0.5];
    for (UIView *view in tabbarcontroller.view.subviews)
    {
        NSLog (@ "%@" , view);

        if ([view isKindOfClass:[UITabBar class ]])
        {
            [view setFrame:CGRectMake(view.frame.origin.x, 431, view.frame.size.width, view.frame.size.height)];
        }
        else
        {
            [view setFrame:CGRectMake(view.frame.origin.x, view.frame.origin.y, view.frame.size.width, 431)];
        }
    }

    [UIView commitAnimations];
}

-( void )viewWillAppear:( BOOL )animated
{
   [ super viewWillAppear:animated];
   [ self hideTabbar: self .tabbarController];
}

-( void )viewWillDisAppear:( BOOL )animated
{
   [ super viewWillDisAppear:animated];
   [ self showTabbar: self .tabbarController];
}

以上代码参考了 http://stackoverflow.com/questions/5272290/how-to-hide-uitabbarcontroller