如何停止跳到导航控制器的选项卡栏的第二个点击? [英] How to stop tab bar's second tap which pops to navigation controller?

问题描述

我有一个基于标签栏的应用程序.所有选项卡均以导航控制器为根.如果用户再次点击该选项卡(如果该选项卡处于活动状态)，它将弹出回到导航控制器.

I have a tab bar based app. All tabs have a navigation controller as the root. If the user taps on the tab again if the tab is active, it pops back to the navigation controller.

如何停止这种行为?

因此，实际上我有一个导航控制器+一个隐藏的 viewcontroller ，它可以做出一些决定+另一个视图控制器.很抱歉原问题中的误导性信息.我对所有选项卡使用了隐藏的 viewcontroller ，其中三个选项卡，因为如果用户未登录，则所有三个选项卡都具有登录屏幕.如果用户登录，则弹出登录屏幕，然后在每个标签上分别放置 1,2,3 个单独的 viewcontrollers .

So in fact I have a navigation controller + a hidden viewcontroller that makes some decisions + another view controller. Sorry for the misleading information in the original question. I use the hidden viewcontroller for all the tabs, 3 of them, since I have the login screen on all 3 if the user is not logged in. If the user logs in, then I pop the login screen, and put the 1,2,3 individual viewcontrollers on each tab.

第一次点击:

 0 : class=Crossing: 0x645c8a0>  
 1 : class=FavoritesViewController: 0x64ac140>  
 shouldSelectViewController : UINavigationController  
 UINavigationController topclass:FavoritesViewController  
 myTabBarController.selectedViewController :UINavigationController  
 did disappear  
 didSelectViewController : UINavigationController  
 UINavigationController topclass:FavoritesViewController  

第二次点击:

 0 : class=Crossing: 0x645c8a0>  
 1 : class=FavoritesViewController: 0x64ac140>  
 shouldSelectViewController : UINavigationController  
 UINavigationController topclass:FavoritesViewController  
 myTabBarController.selectedViewController :UINavigationController  
 didSelectViewController : UINavigationController  
 UINavigationController topclass:Crossing  

推荐答案

@MarkGranoff在执行此操作的正确轨道上，但是执行此操作的方法是执行以下操作:

@MarkGranoff was on the right track for doing this, but the way to do it is by doing something like this:

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    if ([tabBarController.viewControllers indexOfObject:viewController] == tabBarController.selectedIndex)
    {
        return NO;
    }
    else
    {
        return YES;
    }
}

或以不太冗长的方式:

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    return (viewController != tabBarController.selectedViewController);
}

如果您只想阻止某个选项卡的默认行为，则可以执行以下操作:

If you only want to block the default behaviour for a certain tab then you can do something like this:

- (BOOL)tabBarController:(UITabBarController *)tabBarController shouldSelectViewController:(UIViewController *)viewController
{
    NSUInteger indexOfNewViewController = [tabBarController.viewControllers indexOfObject:viewController];
    // Only the second tab shouldn't pop home 
    return ((indexOfNewViewController != 1) ||
            (indexOfNewViewController != tabBarController.selectedIndex));
}

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