ios - Coredata chained Relationship -

what best way update or add data if relationships chained.

i have coredata designed this:

i have 3 entities

1) user to_many category

2) category to_many item

3) item to_one category

user required before adding category, , category required before adding item

simple. set to-one relationship, corresponding inverse relationship set automatically core data.

newitem.category = category category.user = user 

according best practice, renaming clumsy attribute names itemcategory, categoryuser, categoryinuser category, user, categories respectively.