详细信息替换segue后，UISplitView按钮丢失-Java 学习之路

我有一个主题细节iPad界面设置与故事板，以在细节视图控制器上提供替换segue . 这可以很好地替换细节控制器，但在某些情况下缺少显示主控制器的条形按钮 .

如果我在纵向中执行segue，则会缺少bar按钮，因为从不调用 willHideViewController: 委托方法 . 当从主服务器调用 prepareForSegue: 时，我将委托设置为新的详细信息控制器 .

当按钮丢失时，我可以将iPad旋转到横向然后再回到纵向，然后会出现按钮 .

在 prepareForSegue:

UINavigationController *nav = [segue destinationViewController];
    UIViewController *destinationViewController = nav.topViewController;
    if ([destinationViewController conformsToProtocol:@protocol(UISplitViewControllerDelegate)]) {
        self.splitViewController.delegate = destinationViewController;
    }
    else {
        self.splitViewController.delegate = nil;
    }

在细节控制器中：

#pragma mark - Split view

- (void)splitViewController:(UISplitViewController *)splitController willHideViewController:(UIViewController *)viewController withBarButtonItem:(UIBarButtonItem *)barButtonItem forPopoverController:(UIPopoverController *)popoverController
{
    barButtonItem.title = NSLocalizedString(@"MasterButton", @"Master");
    [self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
    self.masterPopoverController = popoverController;
}

- (void)splitViewController:(UISplitViewController *)splitController willShowViewController:(UIViewController *)viewController invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem
{
    // Called when the view is shown again in the split view, invalidating the button and    popover controller.
    [self.navigationItem setLeftBarButtonItem:nil animated:YES];
    self.masterPopoverController = nil;
}

2 回答

我遇到了同样的情况，我通过将当前的detailViewController（正在被替换）中的barButton值传递给prepareForSegue方法中的目标detailViewController（替换的那个）来解决 .

步骤是：

将barButton存储为UISplitViewDelegate方法中的属性

因此，在DetailViewControllers中添加：

@property (nonatomic, strong) UIBarButtonItem *rootPopoverButtonItem;

并在委托方法中：

-(void)splitViewController:(UISplitViewController *)svc willHideViewController:
(UIViewController *)aViewController withBarButtonItem:(UIBarButtonItem *)barButtonItem
 forPopoverController:(UIPopoverController *)pc
{
     barButtonItem.title = @"Master";
     [self.navigationItem setLeftBarButtonItem:barButtonItem animated:YES];
     self.rootPopoverButtonItem = barButtonItem; //Storing the barButton
     self.masterPopoverController = pc;

}

-(void)splitViewController:(UISplitViewController *)svc willShowViewController:
(UIViewController *)aViewController 
invalidatingBarButtonItem:(UIBarButtonItem *)barButtonItem
{

   // Called when the view is shown again in the split view, invalidating the button and popover controller.

    [self.navigationItem setLeftBarButtonItem:nil animated:YES];
    self.rootPopoverButtonItem = nil;  //Storing the barButton
    self.masterPopoverController = nil;

}

现在在你的 - （void）viewDidLoad中读取存储的值并显示 . 如果barButton显示在正被替换的viewController中，则当前VC将显示它 .

[self.navigationItem setLeftBarButtonItem:self.rootPopoverButtonItem animated:YES];

现在在主视图控制器中包含prepareForSegue中的以下内容...

UISplitViewController *splitViewController = (UISplitViewController *)self.view.window.rootViewController;
      UINavigationController *currentNavigationController = [splitViewController.viewControllers lastObject];
      UINavigationController *navigationController = [segue destinationViewController];

      DetailViewController *destinationDetailViewController=(DetailViewController *)[navigationController topViewController];
      DetailViewController *currentDetailViewController =(DetailViewController *)[currentNavigationController topViewController];

      splitViewController.delegate = destinationDetailViewController;//Needed for passing the delegate

      if(currentDetailViewController.rootPopoverButtonItem !=nil)
      {

      destinationDetailViewController.rootPopoverButtonItem = currentDetailViewController.rootPopoverButtonItem;

      }

这不是一种优雅的方法..但对我来说没有太大的开销 . 如果您可以使用SubstitutableDetailViewController协议，还有其他方法（更优雅）可用 . 但它看起来像是太多的工作，而且超越了能力 .

回复于 2024-05-21T14:01:33+08:00

0
在看了iOS8 Day by Day课程后，我终于破解了它，即splitViewController chapter 18.

我遇到的情况与此线程相似 . 最初，SpliViewController使DetailViewController显示'Expand'按钮 . 经过一段时间后，这将消失 . 所以最初的想法是我的SplitViewController， onViewLoad() 触及了DetailViewController . 重新创建DetailViewController后，将无法再现此自定义行为 . 这是我的故事板，因此您可以更轻松地识别代码中的对象：

请注意主控制器和细节控制器都有导航控制器（我知道这是如何让他们用导航条表现的，我真的不知道我是iOS的爱好者 .

所以在逐块注释一些代码之后，在_2582377中我发现了导致这种行为的代码行：
```
let detailNavVC = self.childViewControllers.last as! UINavigationController
    detailNavVC.topViewController!.navigationItem.leftBarButtonItem = self.displayModeButtonItem()
```
现在只需要在DetailController加载的每个时间重新创建此行为：
```
override func viewDidLoad() {
        super.viewDidLoad()
....
if (self.navigationController?.splitViewController?.collapsed == false {
    self.navigationItem.leftBarButtonItem = self.navigationController?.splitViewController?.displayModeButtonItem()}
```
小心，如果你忽略if语句，你也会隐藏iPhone 4S等单细节控制器屏幕上的后退按钮！就是这样，它现在按预期工作！
回复于 2024-05-21T14:01:33+08:00

详细信息替换segue后，UISplitView按钮丢失

2 回答

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