Question

我在我的应用版本之间共享一个Core Data Controller类。

该代码适用于iPhone版本，但在iPad版本上停止了。

这是从RootVC调用的代码：

    #pragma mark - NSFetchedResultsController

    - (NSFetchedResultsController *)fetchedResultsController {
         NSLog(@"%s", __FUNCTION__);
        if (_fetchedResultsController != nil) {
            return _fetchedResultsController;
        }


         // Create the fetch request for the entity   
        NSLog(@"1");
        NSEntityDescription *entity = [NSEntityDescription entityForName:@"Person" inManagedObjectContext:self.managedObjectContext];

 // Set up the fetched results controller

        NSLog(@"2");
        NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
        NSLog(@"3");

        [fetchRequest setEntity:entity];
       NSLog(@"4");
        // Set the batch size to a suitable number
        [fetchRequest setFetchBatchSize:20];

        // Edit the sort key as appropriate.
        NSSortDescriptor *titleSortDesc = [[NSSortDescriptor alloc] initWithKey:@"title" ascending:YES];
        NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:titleSortDesc, nil];

        [fetchRequest setSortDescriptors:sortDescriptors];

        // Edit the section name key path and cache name if appropriate,
        // nil for section name key path means "no sections"
        NSFetchedResultsController *aFetchedResultsController =
            [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                managedObjectContext:self.managedObjectContext
                                                  sectionNameKeyPath:nil
                                                           cacheName:nil];

        aFetchedResultsController.delegate = self;
        self.fetchedResultsController = aFetchedResultsController;

        return _fetchedResultsController;
    }

日志条目1显示。日志条目2未显示。我反而得到了这个崩溃：

2012-11-19 08:37:26.402  I'm an iPad
2012-11-19 08:37:26.400  -[CoreDataController asyncLoadPersistentStores]
2012-11-19 08:37:26.403  -[CoreDataController loadiCloudStore:]
2012-11-19 08:37:26.404  moc is <NSManagedObjectContext: 0x1e03e4f0>
2012-11-19 08:37:26.421  -[CoreDataController iCloudStoreURL]
2012-11-19 08:37:26.454  -[CoreDataController folderForUbiquityToken:]
2012-11-19 08:37:26.460  -[RootViewController viewDidLoad]
2012-11-19 08:37:26.469   RVC moc is (null)
2012-11-19 08:37:26.470  -[RootViewController fetchedResultsController]
2012-11-19 08:37:26.472  1
2012-11-19 08:37:26.474  Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Person''
*** First throw call stack:

我将托管对象上下文从App Delegate传递给RootVC，如下所示：

rootViewController.managedObjectContext = self.coreDataController.mainThreadContext;

我可以用一些帮助搞清楚这一点。我不知道它适用于iPhone和OSX的方式有何不同，而不适用于iPad ..相同的共享数据控制器。

更新：

这些是Phillip评论中提供的日志结果，下面是......

RVC is <RootViewController: 0x1f88d1a0>
-[CoreDataController loadiCloudStore:]
MOC is <NSManagedObjectContext: 0x1eda3630>
-[CoreDataController iCloudStoreURL]
-[RootViewController viewDidLoad]
-[CoreDataController folderForUbiquityToken:]
-[RootViewController fetchedResultsController]
1
SELF is <RootViewController: 0x1f8859d0>

Answer 1

从评论....

在应用程序委托中记录rootViewController地址，并在控制器自己的方法中记录self的相应地址，这表明你有两个不同的RootViewController实例（不同的对象地址），你在那里重新设置moc并不是那个试图用它来生成fetchedResultsController的人。

Core Data Fetch崩溃

1 个答案: