Question

我正在尝试使用NSFetchedResultsController以及与我在App中使用的主MOC不同的其他NSManagedObjectContext。虽然我能够使用额外的MOC保存和检索数据，但每次尝试创建NSFetchedResultsController时，它都会返回一个带有nil fetchedObjects的对象。

我正在使用MagicalRecord，这是我正在使用的代码：

- (id) init
{
    if(SINGLETON){
        return SINGLETON;
    }
    if (isFirstAccess) {
        [self doesNotRecognizeSelector:_cmd];
    }
    self = [super init];
    if (self) {
        NSManagedObjectModel *model = [NSManagedObjectModel MR_newManagedObjectModelNamed:@"ConnectorCache.momd"];
        [NSManagedObjectModel MR_setDefaultManagedObjectModel:model];
        storeCoordinator = [NSPersistentStoreCoordinator MR_coordinatorWithAutoMigratingSqliteStoreNamed:@"ConnectorCache.sqlite"];
        cacheContext = [NSManagedObjectContext MR_contextWithStoreCoordinator:storeCoordinator];

        [MagicalRecord setShouldAutoCreateManagedObjectModel:YES];

    }
    return self;
}

获取fetchedResultsController的代码是：

- (NSFetchedResultsController *) fetchedResultsController {

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

    NSFetchRequest *request = [Appointment MR_requestAllSortedBy:@"start" ascending:YES inContext:cacheContext];
    _fetchedResultController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:cacheContext sectionNameKeyPath:@"day" cacheName:nil];
    return _fetchedResultController;
}

如果我使用请求获取数据，它可以正常工作：

(lldb) po [cacheContext executeFetchRequest:request error:nil];
<_PFBatchFaultingArray 0x7fd9ca576710>(
<Appointment: 0x7fd9ca4c7220> (entity: Appointment; id: 0xd00000000004000a <x-coredata://36BACA76-7C2B-413C-8782-F92BBC7C1AA7/Appointment/p1> ; data: {
    attendees = "<relationship fault: 0x7fd9ca518400 'attendees'>";
    attendeesOmitted = nil;
    created = "2015-03-10 16:41:31 +0000";
    creator = nil;
    end = "2015-03-18 18:45:00 +0000";
    eventDescription = "Doctor Garc\U00eda Villaran";
    eventID = "_8gs3ecpi8h0jab9i6op3ib9k6gp3iba18kojiba68d1j8c2260pj4e1o64";
    lastUpdated = "2015-03-10 16:42:13 +0000";
    location = "Centro M\U00e9dico Quir\U00f3n Sevilla Este, Sevilla, ES";
    start = "2015-03-18 17:45:00 +0000";
    status = 0;
    title = "Cita otorrino";
})
)

我看不出我错过了什么......

亲切的问候

Answer 1

我是我的错，我错过的是我使用的是MagicalRecord，它实际上提供了获取NSFetchedResultsController的方法。

NSManageObject MR_fetchAll ...或朋友将完成这项工作。就我而言，我用过：

_fetchedResultController = [Appointment MR_fetchAllSortedBy:@"start"
                                                      ascending:YES
                                                  withPredicate:nil
                                                        groupBy:@"day"
                                                       delegate:nil
                                                      inContext:cacheContext];

无法使用具有多个上下文的NSFetchedResultsController获取对象

1 个答案: