Question

I’m using the following code to fetch data out of my Core Data graph:

- (void)setupFetchedResultsController
{
    // 1 - Decide what Entity you want
    NSString *entityName = @"Snag"; // Put your entity name here
    NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);

    // 2 - Request that Entity
    NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];

    // 3 - Filter it if you want
    request.predicate = [NSPredicate predicateWithFormat:@"project.id = %@", projectPassedToController.id];

    // 4 - Sort it if you want
    request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"dateTaken"
                                                                                     ascending:YES
                                                                                      selector:@selector(localizedCaseInsensitiveCompare:)]];
    // 5 - Fetch it
    self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
                                                                        managedObjectContext:self.managedObjectContext
                                                                          sectionNameKeyPath:nil
                                                                                   cacheName:nil];

However, I only want to return projects that have the same unique identifier as the one that is being passed to this View Controller (using the ProjectPassedToController variable)

I don’t want to filter by the project.name, as this field is editable by the user. I need to filter by the project’s unique identifier but i’m not sure how to do this.

Answer 1

Solved this by filtering on the relationship between the project and person.

 request.predicate = [NSPredicate predicateWithFormat:@"belongsToProject = %@", _selectedProject];