CODEWITHSUNDEEP
objective-cioscore-datauitableviewnsfetchedresultscontroller
Ilya Ilin
Ilya Ilin

Reputation: 2401

NSFetchedResultsController for new object

I have UITableViewController with static editable cells. In my UITableViewController I make CoreData object, like this:

- (User*)user {
    if (_user == nil) {
        _user = [NSEntityDescription insertNewObjectForEntityForName:TABLE_USER inManagedObjectContext:self.managedObjectContext];
        NSError* error;
        [self.managedObjectContext save:&error];
        if (error != nil) {
            abort();
        }
    }
    return _user;
}

I want to get the object in NSFetchedResultsController that would display its fields in a table, and then save the object. I'm trying to do:

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

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:TABLE_USER_PROFILE inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

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

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"lastName" ascending:NO];
    NSArray *sortDescriptors = @[sortDescriptor];


    NSPredicate* pred = [NSPredicate predicateWithFormat:@"%@ = %@", TABLE_USER, self.user];
    [fetchRequest setPredicate:pred];

    [fetchRequest setSortDescriptors:sortDescriptors];

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

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error]) {
        abort();
    }

    return _fetchedResultsController;
}

But it didn't work. I get empty fetchedResultsController.

Upvotes: 0

Views: 193

Answers (1)

Lorenzo B
Lorenzo B

Reputation: 33428

If self.user is a NSManagedObject and you query against a User entity you could try to edit your predicate like the following:

NSPredicate* pred = [NSPredicate predicateWithFormat:@"self == %@", self.user];

Hope that helps.

P.S. If my answer doesn't work try to provide some other details (see my comment)

Upvotes: 1

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