Core Data NSFetchRequest within specific object using NSPredicate

Question

I have a core data entity, "Entity 1" it has a one to many relationship lets call it "entityRelationship" to another entity "Entity 2".

I'd like to be able to perform a NSFetchRequest for use with a NSFetchResultsController to return the list of "Entity 2" objects for a specific "Entity 1" object.

I have the "Entity 1" stored out as it's own variable, but i can't seem to find the correct way to set up an NSPredicate to return the objects:

Here's my code:

 NSFetchedResultsController *fetchedEvents;
    NSFetchRequest *fetchRequest;
    NSError *error = nil;

    fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Entity2"];
    [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"Entity2 IN self = %@",entity1Object]];
    [fetchRequest setSortDescriptors:@[]];// no sort descriptors
    fetchedEvents = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:theManagedObjectContext sectionNameKeyPath:nil cacheName:nil];
    [fetchedEvents performFetch:&error];

    if (error) {
        NSLog(@"Unable to perform fetch.");
        NSLog(@"%@, %@", error, error.localizedDescription);
    }
    return fetchedEvents;

This crashes with the following error:

** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unable to parse the format string "NSMDEvents IN self = %@"'

Am i doing something wrong? Or is this the incorrect way to go about returning entities with relationships?

Answer 1

Trying the suggested code (thanks vadian) kept causing my app to crash with various errors regarding keys not existing etc, this turned out to be down to a relationship issue.

"Entity2" was inheriting from another entity (had its parent Entity field set in the Data Model Inspector)"Entity 0". However the relationship between "Entity1" was between itself and "Entity0" not "Entity2".

So after a rejig of the core data model "Entity2" had a relationship added (lets call it "EntityEvents") between itself and "Entity1". Now using the following code i was able to select the specific events from the current object:

 NSFetchedResultsController *fetchedEvents;
    NSFetchRequest *fetchRequest;
    NSError *error = nil;

    fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Entity2"];
    [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"EntityEvents == %@",Entity1]];
    [fetchRequest setSortDescriptors:@[]];// no sort descriptors
    fetchedEvents = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:theManagedObjectContext sectionNameKeyPath:nil cacheName:nil];
    [fetchedEvents performFetch:&error];

    if (error) {
        NSLog(@"Unable to perform fetch.");
        NSLog(@"%@, %@", error, error.localizedDescription);
    }

    return fetchedEvents;