cocoa - 对 CoreData 支持的 NSArrayController 进行排序时遇到问题

Question

我正在尝试从我的核心数据支持的 NSArrayController 中检索排序对象的数组。一旦 ManagedObjectContext 准备好，我就会触发一个通知，拥有 NSArrayController 的对象会监听该通知，然后使用 sortDescriptors 设置获取请求。然而，数据从未被排序。我已经为此绞尽脑汁好几个小时了。

我在数组中得到了预期的数据，但它根本没有排序。有人知道我哪里出错了吗？

// Elsewhere in code
...
_charts = [[NSArrayController alloc] init];
_charts.entityName = @"Charts";
...

// When Cored Data and Managed Object Context is ready
-(void)mangagedObjectContextReady
{
    NSManagedObjectContext *moc = ((AppDelegate *)[NSApp delegate]).managedObjectContext;
    _charts.managedObjectContext = moc;
    _charts.usesLazyFetching = NO;
    _charts.automaticallyPreparesContent = YES;
    _charts.automaticallyRearrangesObjects = YES;

    // Create fetch request for data
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    fetchRequest.entity = [NSEntityDescription entityForName:@"Charts" inManagedObjectContext:moc];

    // Create the sort descriptors for the Charts entity
    // Name and chartType are properties on the entity "Charts"
    NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(caseInsensitiveCompare:)];
    NSSortDescriptor *chartTypeDescriptor = [[NSSortDescriptor alloc] initWithKey:@"chartType" ascending:YES selector:@selector(caseInsensitiveCompare:)];
    fetchRequest.sortDescriptors = @[nameDescriptor, chartTypeDescriptor];

    NSError *error = nil;
    BOOL success = [_charts fetchWithRequest:fetchRequest merge:NO error:&error];
    if(!success)
        NSLog(@"Error %@:", [error localizedDescription]);
    else {
       [_charts rearrangeObjects];
       [_tv reloadData];
    }

我使用此方法来获取数组或已排序的对象..但数据未按照上述排序描述符进行排序？

[_charts.arrangedObjects objectAtIndex:row]

Answer 1

_charts.sortDescriptors = @[nameDescriptor，chartTypeDescriptor];