I'm wondering how to share an entity between two different core data models?
For example, I have a "Universe" model which describes a "WorldData" with its "CountryData". And in another hand, I have a "Population" model which describes a "HumanData" with its "CountryData".
I definitely want to keep my models separated.
Thanks in advance.
Have you checked the Core Data Guide? Managing relationships between entities is pretty basic.
If you want to manage a relationship between your Universe entities and your Population entities, you should describe them in the same model. Off the top of my head, I can't think of any benefits of putting two related entities in different Core Data Models.