Core Data to-many relationships. Are they Lazy Load?

Question

I have the typical model in Core Data (for iPhone) with Departments and Employesss (Department ->> Employee).

I dont want to load all employees of a department each time

Answer 1

No, objects related to to-many and to-one relationships are loaded lazily by default. However, If you need to access many of them each time you fetch a Department, then for performance reasons you may ask Core Data to load them simultaneously (this is called pre-fetching). You can do this as follow:

[fetchRequest setReturnsObjectsAsFaults:NO];
[fetchRequest setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObjects:@"employees", nil]];