How to get objects of related indirectly by NSPredicate?

Question

I have three model in CoreData:

• Category with categoryId
• Production with productionId
• SubProduction with subProductionId

SubProduction is related to One Production and every product has Many SubProduction

Production is related to One Category and every Category has Many Production

I want to get all SubProduction of a Category by categoryId.

I know this way: Load all productions of category and by a for loop get all SubProductions. I'm wondering if there is a better way to approach it by NSPredicate

How to make this NSPredicate format?

Something like this:

frc.fetchRequest.predicate = NSPredicate(format: "production.category = %@", category)

Answer 1

WOW, I just test my imagine and

It's work:

frc.fetchRequest.predicate = NSPredicate(format: "production.category = %@", category)

Thanks to NSPredicate