Core data 即使我正在更新托管对象，Coredata也没有更新

如您所见，“ZMESSAGEID”字段包含值“CLUBID_7y9198983003160187157002809ee1qzg6eeieguz47tqvm67rs377jjb_gft.jpg”应该有1条记录，而不是3条。当我试图使用托管对象进行更新时，在coredata中保存上下文后，出现了下面的附加图像

当相关消息（CLUBID_7Y9198983003160187157002809EE1QZG6EEIEGUZ47TQVM67RS377JJB_gft.jpg）没有数据时，使用以下代码插入：

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上载图像后，我尝试使用以下代码段将“ZFILEUPLOADED”字段设置更改为0：

NSManagedObjectContext *context = [HQXMPPManager shareXMPPManager].msgStorage.mainThreadManagedObjectContext;
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"XMPPMessageArchiving_Message_CoreDataObject"];
    NSError *error = nil;
    NSPredicate *pre = [NSPredicate predicateWithFormat:@"messageId = %@",messageId];
    NSLog(@"QUERY For messageId: %@ %@",pre,messageId);
    request.predicate = pre;
    NSArray *aryResults = [context executeFetchRequest:request error:&error];
    for (XMPPMessageArchiving_Message_CoreDataObject *msg in aryResults)
    {
 [msg setValue:@"0" forKey:@"fileUploaded"];
NSError *err = nil;
 [context save:&err];


}

NSManagedObjectContext *context = [HQXMPPManager shareXMPPManager].msgStorage.mainThreadManagedObjectContext;
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:@"XMPPMessageArchiving_Message_CoreDataObject"];
    NSError *error = nil;
    NSPredicate *pre = [NSPredicate predicateWithFormat:@"messageId = %@",messageId];
    NSLog(@"QUERY For messageId: %@ %@",pre,messageId);
    request.predicate = pre;
    NSArray *aryResults = [context executeFetchRequest:request error:&error];
    for (XMPPMessageArchiving_Message_CoreDataObject *msg in aryResults)
    {
 [msg setValue:@"0" forKey:@"fileUploaded"];
NSError *err = nil;
 [context save:&err];


}