NSPredicate with a !=?

Question

I have Core Data Entities Person and Boundary. They have a many-to-many relationship (each person can have many boundaries, and each boundary can have many persons).

I a

Answer 1

you need to ask first in Class Boundary if there is a person called Fred that has boundaries. It should be something like:

NSFetchRequest* fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Boundary"];
fetchRequest.predicate = [NSPredicate predicateWithFormat:@"ANY persons.name != %@", person.name];

That will fetch all the boundaries that Fred doesn't have.

Answer 2

[NSPredicate predicateWithFormat:@"ANY persons != %@", fred]

finds all objects that are related to any person other that Fred. What you want is

[NSPredicate predicateWithFormat:@"NOT(ANY persons = %@)", fred]

and this should return all objects that are not related to Fred.

However, there seems to be a Core Data bug that "NOT ANY" or "NONE" do not work correctly in a predicate, compare NSPredicate Aggregate Operations with NONE. The workaround is to use a SUBQUERY:

[NSPredicate predicateWithFormat:@"SUBQUERY(persons, $p, $p == %@).@count == 0", fred]