详细信息替换segue后,UISplitView按钮丢失

Question

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,则会丢失条形按钮,因为willHideViewController:从不调用委托方法.prepareForSegue:从主服务器调用时,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;
}

Answer 1

我遇到了同样的情况，我通过在prepareForSegue方法中将barButton值从当前detailViewController（正在被替换）传递到目标detailViewController（正在替换的）来解决。

步骤是：

1. 将 barButton 作为属性存储在 UISplitViewDelegate 方法中

   因此，在 DetailViewControllers 中添加：

   @property (nonatomic, strong) UIBarButtonItem *rootPopoverButtonItem;
   

   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;
   
   }
   

2. 现在在您的 - (void)viewDidLoad 中读取存储的值并显示。如果 barButton 显示在要替换的 viewController 中，则当前 VC 将显示它。

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

3. 现在在主视图控制器中的prepareForSegue中包含以下内容...

         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;
   
         }
   

这不是一个优雅的方法..但对我来说没有太多开销。如果您可以使用 SubstitutableDetailViewController 协议，还有其他方法（更优雅）可用。但看起来工作量太大了，而且超出了能力范围。