Coredata无法删除已有记录+多线程

Question

我正在解析xml，在数据库中插入一个实体，用于更新记录，我再次添加该记录并删除较旧的记录。但是它不能删除较旧的条目，所以我可以看到重复的条目。

- (void)insertSampleWithId:(NSString *)sampleId{

    __block NSError *lError = nil;

    dispatch_queue_t categoryCustomQueue = dispatch_queue_create("com.xyz.sample”, NULL);

    dispatch_sync(categoryCustomQueue, ^{

        NSNotificationCenter *dnc = [NSNotificationCenter defaultCenter];

        [dnc addObserver:self
                selector:@selector(mergeChanges:)
                    name:NSManagedObjectContextDidSaveNotification
                  object:_tempMOC];


        _supplier = [NSEntityDescription insertNewObjectForEntityForName:@"BSSample” inManagedObjectContext:_tempMOC];
        _supplier.sampleId = supplierId;

//        double delayInSeconds = 0.3;
//        dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
//        
//        dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
//            
       // });

        [self ifSupplierPresentInMainContextRemoveIt:supplierId];

        if(![_tempMOC save:&lError]){

            NSLog(@"Error adding while category %@ ,%@ ,%@", lError, [lError userInfo], [lError localizedDescription]);
        }

        [dnc removeObserver:self name:NSManagedObjectContextDidSaveNotification object:_tempMOC];

    });

}


- (BOOL)ifSamplePresentInMainContextRemoveIt:(NSString *)sampleId{

    __block BSSampler *suppl = nil;

    NSManagedObjectContext *managedObjectContext  = dataManager.coreDataHelper.context;

    NSEntityDescription *entityDescription = [NSEntityDescription
                                              entityForName:@"BSSample” inManagedObjectContext:managedObjectContext];


    [_fetchRequest setEntity:entityDescription];

    [_fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"sampleId == '%@'", supplierId]];
    [_fetchRequest setResultType:NSDictionaryResultType];

    [_fetchRequest setReturnsDistinctResults:YES];
    NSError *error;
    NSArray *array = [managedObjectContext executeFetchRequest:_fetchRequest error:&error];


    if(array != nil && [array count]>0){
        suppl = [array objectAtIndex:0];
    }

    if(suppl)
    [dataManager.coreDataHelper.context deleteObject:suppl];
    return [dataManager.coreDataHelper.context save:&error];

}

- (void)mergeChanges:(NSNotification *)saveNotification{

    [self performSelectorOnMainThread:@selector(mergeToMainThred:) withObject:saveNotification waitUntilDone:NO];
}


- (void)mergeToMainThred:(NSNotification*)saveNotification{

    [dataManager.coreDataHelper.context mergeChangesFromContextDidSaveNotification:saveNotification];
}

Answer 1

这里没有显示删除的代码。

你说不能删除，但你没说为什么或怎么删除。失败的原因是什么？您的期望是什么?实际结果是什么？

mergeChanges:是什么样子的？

请更新您的问题，以便我们有机会了解问题。