在 iOS 8 中 UISplitViewController 的主视图中有一个 UINavigationController

Question

在我的UISplitViewController 中，主视图是一个包含UITableViewController 的UINavigationController。有时，当用户在表中选择一个项目时，我必须在主视图中的现有表上推送另一个 UITableViewController。

在 iOS 7 中，在我的第一个 UITableViewController 中，我只是调用

[self.navigationController pushViewController:otherTableVC animated:YES];

在 iOS 8 中：

当拆分视图折叠时，otherTableVC 变成了详细视图！ 然后旋转设备后，我们看到两张桌子并排...

更糟糕的是，如果设备显示两个窗格，则代码运行良好，并且第二个表格在主视图中被推到第一个表格之上。但是，在两次旋转之后，两张桌子又是并排的。 UISplitViewController 的折叠模式似乎干扰了我自己的导航控制器……

如何在主视图中管理我自己的UINavigationController？

谢谢

已编辑：

我的主要视图和细节视图都有一个导航控制器。为了解决我的问题，我刚刚发现，在折叠模式下，我必须创建一个额外的导航控制器并将其推送到主导航控制器上。

UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:otherTableVC];
[self.navigationController pushViewController:navController animated:YES];

所以我刚刚发现我们可以将导航控制器推入另一个导航控制器。

Answer 1

简短的回答，您可以通过 UISplitViewControllerDelegate 方法控制此行为：

splitViewController:collapseSecondaryViewController:ontoPrimaryViewController:
splitViewController:separateSecondaryViewControllerFromPrimaryViewController:

我怀疑你真正想要做的是处理你有一个基于 iOS 8 UISplitViewController 的应用程序的情况，其中你的主要和详细视图都是 UINavigationControllers 并且有一些你想要的 viewControllers（在这些导航控制器中）仅出现在拆分视图的主要或详细信息侧。下面的答案涉及到这个问题。它还可以处理您有时希望视图替换 Detail 导航控制器中的视图，而不是被推送到那里的情况。

一个小警告：下面的代码并没有处理所有可能的情况，并且有一些假设：

• 我们预计，当拆分视图折叠并且这些视图被其上方的详细视图遮挡时，详细导航控制器堆栈上不会发生任何变化。
• 我们的 UIViewController 子类都有一个 shouldDisplayInDetailedView 和 shouldReplaceDetailedView 属性
• 我们假设我们只将视图推送到设置了 shouldDisplayInDetailedView 属性的详细导航控制器上。
• 视图控制器通过 splitViewController:showDetailViewController: 或 pushViewController:animated: 在详细视图中的视图的 navigationController 属性上添加到详细信息端（处于展开或折叠状态）。
• 应该替换 Detail 导航控制器中的视图控制器的视图控制器只能通过 splitViewController:showDetailViewController: 添加，并且只能通过与主视图控制器中的视图交互，即，只有在以下情况下才会发生这种情况处于折叠状态时，主视图控制器不会被遮挡。
• 当拆分视图控制器展开时，我们有一个 BlankViewController 显示在详细视图中，但我们只有应保留在主端的视图控制器。

我不建议只实现 splitViewController:collapseSecondaryViewController:ontoPrimaryViewController: / splitViewController: separateSecondaryViewControllerFromPrimaryViewController: 逻辑的一侧，并取决于另一侧的默认实现。 Apple 做了一些奇怪的事情，比如将 UINavigationViewController 从 Detail 端放入主端，作为主导航控制器堆栈中的 viewControllers 之一，然后将其他视图控制器推到它上面，即使你完全理解仍然无法复制你自己的代码。因此，最好自己处理流程的双方。

这是我用的：

#pragma mark -
#pragma mark Split View Controller delegate.

- (BOOL)splitViewController:(UISplitViewController *)splitViewController showViewController:(UIViewController *)vc sender:(id)sender
{
    //Standard behaviour.  This won't get called in our case when the split view is collapsed and the primary view controllers are obscured.
    return NO;
}

// Since we treat warnings as errors, silence warning about unknown selector below on UIViewController subclasses.
#pragma GCC diagnostic ignored "-Wundeclared-selector"


- (BOOL)splitViewController:(UISplitViewController *)splitViewController showDetailViewController:(UIViewController *)vc sender:(id)sender
{
    if (splitViewController.collapsed == NO)
    {
        // The navigation controller we'll be adding the view controller vc to.
        UINavigationController *navController = splitViewController.viewControllers[1];

        UIViewController *topDetailViewController = [navController.viewControllers lastObject];
        if ([topDetailViewController isKindOfClass:[BlankViewController class]] ||
           ([vc respondsToSelector:@selector(shouldReplaceDetailedView)] && [vc performSelector:@selector(shouldReplaceDetailedView)]))
        {
            // Replace the (expanded) detail view with this new view controller.
            [navController setViewControllers:@[vc] animated:NO];
        }
        else
        {
            // Otherwise, just push.
            [navController pushViewController:vc animated:YES];
        }
    }
    else
    {
        // Collapsed.  Just push onto the conbined primary and detailed navigation controller.
        UINavigationController *navController = splitViewController.viewControllers[0];
        [navController pushViewController:vc animated:YES];
    }

    // We've handled this ourselves.
    return YES;
}

- (BOOL)splitViewController:(UISplitViewController *)splitViewController collapseSecondaryViewController:(UIViewController *)secondaryViewController ontoPrimaryViewController:(UIViewController *)primaryViewController
{
    UINavigationController *primaryNavController = (UINavigationController *)primaryViewController;
    UINavigationController *secondaryNavController = (UINavigationController *)secondaryViewController;
    UIViewController *bottomSecondaryView = [secondaryNavController.viewControllers firstObject];
    if ([bottomSecondaryView isKindOfClass:[BlankViewController class]])
    {
        NSAssert([secondaryNavController.viewControllers count] == 1, @"BlankViewController is not only detail view controller");
        // If our secondary controller is blank, do the collapse ourself by doing nothing.
        return YES;
    }

    // We need to shift these view controllers ourselves.
    // This should be the primary views and then the detailed views on top.
    // Otherwise the UISplitViewController does wacky things like embedding a UINavigationController inside another UINavigation Controller, which causes problems for us later.
    NSMutableArray *newPrimaryViewControllers = [NSMutableArray arrayWithArray:primaryNavController.viewControllers];
    [newPrimaryViewControllers addObjectsFromArray:secondaryNavController.viewControllers];
    primaryNavController.viewControllers = newPrimaryViewControllers;

    return YES;
}

- (UIViewController *)splitViewController:(UISplitViewController *)splitViewController separateSecondaryViewControllerFromPrimaryViewController:(UIViewController *)primaryViewController
{
    UINavigationController *primaryNavController = (UINavigationController *)primaryViewController;

    // Split up the combined primary and detail navigation controller in their component primary and detail view controller lists, but with same ordering.
    NSMutableArray *newPrimaryViewControllers = [NSMutableArray array];
    NSMutableArray *newDetailViewControllers = [NSMutableArray array];
    for (UIViewController *controller in primaryNavController.viewControllers)
    {
        if ([controller respondsToSelector:@selector(shouldDisplayInDetailedView)] && [controller performSelector:@selector(shouldDisplayInDetailedView)])
        {
            [newDetailViewControllers addObject:controller];
        }
        else
        {
            [newPrimaryViewControllers addObject:controller];
        }
    }

    if (newDetailViewControllers.count == 0)
    {
        // If there's no detailed views on the top of the navigation stack, return a blank view  (in navigation controller) for detailed side.
        UINavigationController *blankDetailNavController = [[UINavigationController alloc] initWithRootViewController:[[BlankViewController alloc] init]];
        return blankDetailNavController;
    }

    // Set the new primary views.
    primaryNavController.viewControllers = newPrimaryViewControllers;

    // Return the new detail navigation controller and views.
    UINavigationController *detailNavController = [[UINavigationController alloc] init];
    detailNavController.viewControllers = newDetailViewControllers;
    return detailNavController;
}

Answer 2

Swift 4 版本稍作改动以使其适用于我的代码：

func splitViewController(_ splitViewController: UISplitViewController, showDetail vc: UIViewController, sender: Any?) -> Bool {
    if !isCollapsed {
        // in expanded mode set new VC as top view controller of the detail nav controller
        if let detailNavigationController = viewControllers[1] as? UINavigationController {
           detailNavigationController.setViewControllers([vc], animated: false)
        }
    } else {
        // in collapsed mode push the new view controller on the master nav controller
        if let masterNavigationController = viewControllers[0] as? UINavigationController {
            masterNavigationController.pushViewController(vc, animated: true)
        }
    }
    return true
}

func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController: UIViewController, onto primaryViewController: UIViewController) -> Bool {

    let masterNavigationController = primaryViewController as? UINavigationController
    let detailNavigationController = secondaryViewController as? UINavigationController
    let episodeDetailViewController = detailNavigationController?.viewControllers.first as? EpisodeDetailTableViewController
    if episodeDetailViewController?.episode == nil {
        // detail view is blank. We do not need to push this onto the master
        return true
    }

    guard var newMasterViewControllers = masterNavigationController?.viewControllers else { return false }
    newMasterViewControllers.append(contentsOf: detailNavigationController?.viewControllers ?? [])
    masterNavigationController?.setViewControllers(newMasterViewControllers, animated: false)
    return true
}


func splitViewController(_ splitViewController: UISplitViewController, separateSecondaryFrom primaryViewController: UIViewController) -> UIViewController? {
    let masterNavigationViewController = primaryViewController as? UINavigationController

    var newMasterViewControllers = [UIViewController]()
    var newDetailViewControllers = [UIViewController]()

    for vc in masterNavigationViewController?.viewControllers ?? [] {
        if vc is PodcastsTableViewController || vc is EpisodesTableViewController {
            newMasterViewControllers.append(vc)
        } else {
            newDetailViewControllers.append(vc)
        }
    }

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let detailNavigationController = storyboard.instantiateViewController(withIdentifier: "splitViewDetailViewController") as! UINavigationController

    if newDetailViewControllers.count == 0 {
        let emptyEpisodeDetailViewController = storyboard.instantiateViewController(withIdentifier: "episodeDetail")
        newDetailViewControllers.append(emptyEpisodeDetailViewController)
    }

    masterNavigationViewController?.setViewControllers(newMasterViewControllers, animated: false)
    detailNavigationController.setViewControllers(newDetailViewControllers, animated: false)
    return detailNavigationController
}