NSFetchedResultsController 错误：

Question

使用 NSFetchedResultsController 将新记录插入我的 CoreData 存储后，当我尝试在分组的 UITableView 中显示数据时，应用程序崩溃并出现以下错误“

NSFetchedResultsController ERROR: The fetched object at index 5 has an out of order section name 'Navigation. Objects must be sorted by section name'

我已将部分键值添加到 sortDescriptors，但它没有帮助。这是我的代码：

- (NSFetchedResultsController *)fetchedResultsController {

if (fetchedResultsController != nil) {
    return fetchedResultsController;
}

/*
 Set up the fetched results controller.
 */
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Item" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];

// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];

// Edit the sort key as appropriate.
NSSortDescriptor *sortByGroupName = [[NSSortDescriptor alloc] initWithKey:@"group.groupName" ascending:NO];
NSSortDescriptor *sortByIsMandatory = [[NSSortDescriptor alloc] initWithKey:@"isMandatory" ascending:NO];
NSSortDescriptor *sortByItemName = [[NSSortDescriptor alloc] initWithKey:@"itemName" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortByGroupName, sortByIsMandatory, sortByItemName, nil];

[fetchRequest setSortDescriptors:sortDescriptors];

// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:@"group.groupName" cacheName:@"Root"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;

[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptors release];
[sortDescriptors release];

return fetchedResultsController;

}

我在这里错过了什么？

谢谢--

Jk

Answer 1

哇！发现我的问题：我过度释放了 sortDescriptors

Answer 2

但是您正在泄漏各个 sortDescriptors sortByGroupName，等等。你也应该释放它们。