CoreData - Is there a good way to upsert items?

Just wondering whether there is a good way to upsert items in a CoreData db?

Or is there a way for me to consider a CoreData db as a set?

I mean, if I insert an item into the db and if there is already an identical redundant item there, the db ignores it. Any way to conveniently do it? or I have to query each time when I insert in order to avoid redundancy?