使用NSFetchedResultsController创建表节

NSFetchedResultsController UITableViewController . 我正在获取的托管对象的简化版本如下所示(例如:

Person:
-(BOOL)hasPet;
-(BOOL)hasDog;

基本上,我希望我的桌子只显示这些 Person 有宠物的对象。这很简单,我可以使用谓词。现在,对于那些 hasPet == YES ,我想把它们分两部分放在表中,第一部分 hasDog == YES ,第二个是 hasDog == NO

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

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

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"hasPet == %@", [NSNumber numberWithBool:YES]];
[fetchRequest setPredicate:predicate];

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

[fetchRequest setSortDescriptors:sortDescriptors];

NSFetchedResultsController *aController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:nil];
aController.delegate = self;
self.fetchedResultsController = aController;

    // Release things

return fetchedResultsController;
}

是我需要集中注意力的分类描述符吗?