3

为了从我为表格视图单元格调用 Entry 的实体获取信息，我有以下代码：

Entry *entry = [self.appDelegate.fetchedResultsController objectAtIndexPath:indexPath];

    NSLog(@"timeline entry contexts: %@ and %@", [[AppDelegate applicationDelegate] managedObjectContext], [entry managedObjectContext]);

两个 managedObjectContexts 返回不同。这是我获取的结果控制器：

- (NSFetchedResultsController *)fetchedResultsController {

    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Entry" inManagedObjectContext:[AppDelegate applicationDelegate].managedObjectContext];
    [fetchRequest setEntity:entity];

    [fetchRequest setFetchBatchSize:20];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creationDate" ascending:NO];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

    [fetchRequest setSortDescriptors:sortDescriptors];

    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:[AppDelegate applicationDelegate].managedObjectContext sectionNameKeyPath:@"sectionIdentifier" cacheName:@"Root"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    self.fetchedResultsController.delegate = self;

    return _fetchedResultsController;
}

这是我的 MOC：

- (NSManagedObjectContext *)managedObjectContext {

    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];

    if (coordinator != nil) {
        NSManagedObjectContext* moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];

        [moc performBlockAndWait:^{
            [moc setPersistentStoreCoordinator: coordinator];
            [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(mergeChangesFrom_iCloud:) name:NSPersistentStoreDidImportUbiquitousContentChangesNotification object:coordinator];
        }];
        _managedObjectContext = moc;

        _managedObjectContext.mergePolicy = [[NSMergePolicy alloc]
                                            initWithMergeType:NSMergeByPropertyObjectTrumpMergePolicyType];
    }

    return _managedObjectContext;
}

我不确定为什么它会返回不同的 MOC。有什么想法吗？

4

1 回答 1

0

您可以在执行声明根的请求之前尝试清除缓存根

    [NSFetchedResultsController deleteCacheWithName:@"Root"];
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:[AppDelegate applicationDelegate].managedObjectContext sectionNameKeyPath:@"sectionIdentifier" cacheName:@"Root"];

我最近遇到了类似的事情并解决了问题

于 2013-02-05T13:17:33.647 回答