How to create an NSFetchRequest which filters Core Data objects based on attributes AND relationships?

Question

I have a Core Data model setup like so:

• Blockbuster Entity
  • To-Many relationship to DVD entities.

Answer 1

You can traverse relationships in an NSPredicate. For example, you could write something like

[NSPredicate predicateWithFormat:@"title == %@ AND blockbuster.name LIKE \"Blockbuster C\"", @"Transformers 2"]

Now, if you don't have a property to compare against and you need to check actual objects, then you could use something like

[NSPredicate predicateWithFormat:@"title == %@ AND blockbuster IN %@", @"Transformers 2", setOfBlockbusters]

The full syntax is documented here. But setOfBlockbusters could be a set, an array, or a dictionary (if it's a dictionary, the values, not the keys, are used).