iOS：TabBarController 显示/隐藏第一级页面的TabBar

- (void)setTabBarHidden:(BOOL)hidden
{
    UIView *tab = self.tabBarController.view;

    if ([tab.subviews count] < ) {
        return;
    }
    UIView *view;

    if ([[tab.subviews objectAtIndex:] isKindOfClass:[UITabBar class]]) {
        view = [tab.subviews objectAtIndex:];
    } else {
        view = [tab.subviews objectAtIndex:];
    }

    if (hidden) {
        view.frame = tab.bounds;
    } else {
        view.frame = CGRectMake(tab.bounds.origin.x, tab.bounds.origin.y, tab.bounds.size.width, tab.bounds.size.height);
    }
    self.view.frame = view.frame;
    self.tabBarController.tabBar.hidden = hidden;
}