Question

我正在利用一种背景线索来收集迄今为止分类的记录数量有限。

一切工作都很顺利。我删除了在国歌中的记录(表3)。

//this is done in the background thread
NSFetchRequest *frequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"MyEntity" 
                                            inManagedObjectContext:self.managedObjectContext];
[frequest setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc]
                                    initWithKey:@"date"     
                                    ascending:NO];

NSArray *descriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[frequest setSortDescriptors:descriptors];

[frequest setFetchOffset:fetchOffset];    
[frequest setFetchLimit:20];

[frequest setResultType:NSManagedObjectIDResultType];

 NSError *fetchError;
 NSMutableArray *mutableFetchResults = [[self.managedObjectContext executeFetchRequest:frequest 
                                                                               error:&fetchError] mutableCopy];

国家扫盲和扫盲局(NSManagedObjectContextDidSaveNoification)的背景资料已经登记,并担任以下选任者。

//this is done in the background thread
-(void) didSavePersistenceStore:(NSNotification *)notification
{
    [self.managedObjectContext mergeChangesFromContextDidSaveNotification:notification];
}

The problem: After deleting a record, subsequent fetch results are not sorted with date anymore.

What am I missing ?

Answer 1

第一,确保你不使用管理办法反对案文与错误的解读。你们可以呼吁在适当的情况下这样做。

Second, the fetch descriptor you use for the fetch does not persist. So, unless you keep fetching with the same sorting criteria, you won t get it that way.

如果你想要这种行为,就使用独一无二的成果控制器。它将保持对数据库的预期看法。

Answer 2

从果树文献中获取:

If you set the value to NSManagedObjectIDResultType, this will demote any sort orderings to “best efforts” hints if you do not include the property values in the request.

您需要撰写对持久性储存或固定储存的所有改动。待填补。

友情链接