显示一个可放松的视图从AppDelegate基于核心焦点搜索词

I have Core Spotlight set up in my app. I navigate to a specific view controller within a navigation controller that displays a webview webpage based on the title. So for example:

我在app中设置了核心聚光灯。我在导航控制器中导航到一个特定的视图控制器，该控制器根据标题显示一个webview页面。举个例子:

- (BOOL)application:(UIApplication *)application continueUserActivity:(NSUserActivity *)userActivity restorationHandler:(void(^)(NSArray *restorableObjects))restorationHandler {

if ([[userActivity activityType] isEqualToString:CSSearchableItemActionType]) {
    // This activity represents an item indexed using Core Spotlight, so restore the context related to the unique identifier.
    // The unique identifier of the Core Spotlight item is set in the activity’s userInfo for the key CSSearchableItemActivityIdentifier.

    NSString *uniqueIdentifier = [userActivity.userInfo objectForKey:CSSearchableItemActivityIdentifier];
    NSString *valueForUID = [self valueForKey:uniqueIdentifier];

    self.tabBar = (UITabBarController *)self.window.rootViewController;
    self.tabBar.selectedIndex = 0;
    UINavigationController *selectedNav=(UINavigationController *)self.tabBar.selectedViewController;
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
    WebViewController *webVCVC = [storyboard instantiateViewControllerWithIdentifier:@"WebViewController"];
    webVC.title = uniqueIdentifier;
    webVC.titleDetail = valueForUID;
    [selectedNav presentViewController:webVC animated:YES completion:nil];
}
}

In short, the webVC loads a specific web page based on it's self.title and titleDetail, these values change because every spotlight unique ID is different.

简而言之，webVC基于它自己加载一个特定的web页面。标题和titleDetail，这些值会改变，因为每个spotlight惟一ID都是不同的。

The issue isn't if the first spotlight index is selected, everything works fine. however, if I select the new 'Back To %@' button and go back to Spotlight to select a new search item, I get the following error:

问题不是如果选择了第一个焦点指数，一切都很好。但是，如果我选择新的“返回到%@”按钮并返回Spotlight以选择新的搜索项，我将得到以下错误:

Warning: Attempt to present <WebViewController: 0x7fced37c8be0> on <UINavigationController: 0x7fced403fa00> whose view is not in the window hierarchy!

So I thought all I had to do was dismiss the current view every time and reload it:

所以我想我所要做的就是每次都取消当前视图并重新加载它:

self.tabBar = (UITabBarController *)self.window.rootViewController;
self.tabBar.selectedIndex = 0;
UINavigationController *selectedNav=(UINavigationController *)self.tabBar.selectedViewController;
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
WebViewController *webVC = [storyboard instantiateViewControllerWithIdentifier:@"WebViewController"];
[webVC dismissViewControllerAnimated:NO completion:^{
   webVC.title = pubNum;
   webVC.titleString = pubTitle;
   [selectedNav presentViewController:webVC animated:YES completion:nil];
}];

This doesn't work either, I get the following warning/error:

这也不起作用，我得到以下警告/错误:

Attempting to load the view of a view controller while it is deallocating is not allowed and may result in undefined behavior

Which makes sense. How do i circumvent this in this particular instance?

这是有意义的。在这个特定的例子中，我如何规避这个问题?

2 个解决方案

#1

A UINavigationController, even though it inherits from UIViewController, doesn't have a non-nil view of its own, so you can't call presentViewController:animated:completion: on top of it. I think that you're confusing presentViewController (which displays a modal, and needs to be sent to the view controller that's currently being displayed) with pushViewController:animated:, which is sent to the current view controller's navigationController.

UINavigationController，即使它从UIViewController继承，也没有它自己的非nil视图，所以你不能调用presentViewController:animated:completion: on top of it。我认为你混淆了presentViewController(显示一个模态，需要发送给当前显示的视图控制器)和pushViewController:animated:，它被发送给当前视图控制器的navigationController。

#2

I fixed it by dismissing it from the navigation controller:

我把它从导航控制器中删除了:

//Instead of this
[webVC dismissViewControllerAnimated...

//I used this
[selectedNav.presentedViewController dismissViewControllerAnimated...