ios - 如何在NSManagedContext中知道NSManagedObject的类型

Question

我正在使用NSFetchedResultsController从Core Data获取数据，并在UITableView中显示它们。我的NSFetchedResultsController看起来像这样:

- (NSFetchedResultsController *) fetchedResultsController
{
    if (_fetchedResultsController != nil)
    {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"PlanPreparation"
                                              inManagedObjectContext:_context];
    [fetchRequest setEntity:entity];

    NSPredicate *pred = [NSPredicate predicateWithFormat:@"plan_id == %@", _planCycleID];
    [fetchRequest setPredicate:pred];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor, nil];

    fetchRequest.sortDescriptors = sortDescriptors;

    _fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest managedObjectContext:_context sectionNameKeyPath:nil cacheName:nil];
    _fetchedResultsController.delegate = self;

    // but if there is no results I am making another fetch by another type of NSManagedObject    
    if (_fetchedResultsController.fetchedObjects.count == 0)
    {
        NSFetchRequest *fetchRequest1 = [[NSFetchRequest alloc] init];
        NSEntityDescription *entity1 = [NSEntityDescription entityForName:@"Preparation"
                                                  inManagedObjectContext:_context];
        [fetchRequest1 setEntity:entity1];
         NSPredicate *pred = [NSPredicate predicateWithFormat:@"ismer == %@", [NSNumber numberWithInt:1]];
        [fetchRequest1 setPredicate:pred];

        NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
        NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor, nil];

        fetchRequest1.sortDescriptors = sortDescriptors;

        _fetchedResultsController = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest1 managedObjectContext:_context sectionNameKeyPath:nil cacheName:nil];
        _fetchedResultsController.delegate = self;        

        //return _fetchedResultsController;
    }

    return _fetchedResultsController;
}

如果第一次尝试获取内容后我没有重新获取东西，则需要设置另一个获取内容。在 -cellForRowAtIndexPath中，我需要显示数据取决于 NSManagedObjectObject的类型:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }
    if ([[self.fetchedResultsController objectAtIndexPath:indexPath] isKindOfClass:[PlanPreparation2 class]])
    {
        PlanPreparation2 *planDrug = (PlanPreparation2 *)[self.fetchedResultsController objectAtIndexPath:indexPath];
        CDPreparation *prep = (CDPreparation *)[[PTDataManager sharedManager]getDrugByID:planDrug.guid];
        cell.textLabel.text = [NSString stringWithFormat:@"%@", prep.name];
    }
    else
    {
        CDPreparation *drug = (CDPreparation *)[self.fetchedResultsController objectAtIndexPath:indexPath];
        cell.textLabel.text = [NSString stringWithFormat:@"%@", drug.name];
    }

    return cell;
}

但是日志记录表明 -isKindOfClass:在这里不起作用，我根本没有引号。

题:

如何找出 NSManagedObjectObject的类型？

Answer 1

如图所示，在该实体的数据模型检查器中更改名称和类

数据模型检查器中的名称和类字段必须与实体表的名称相同。

然后你可以比较像

if([(NSManagedObject *)[self.fetchedResultsController objectAtIndexPath:indexPath] isKindOfClass:[Category class]])

因为在我的情况下，“类别”是类，所以您可以在上面的[PlanPreparation2类]中选择自己的类

如果仍然遇到问题，请在下面评论