Use NSFetchRequest to get all results of relationship

Question

I have two entities: Author and Book. I want to get the list of all books by a particular author.

Here's the code I'm using:

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Books"];
[fetchRequest setPredicate[NSPredicate predicateWithFormat:@"ANY author == %@", author]];
books = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

However, this returns only one book of the author.

How can I get ALL books of a particular author?

I read a bunch of other topics but none of the solutions seem to work for me.

Thanks!

Answer 1

The issue was in the data model: relationship author -> book should be "To many" instead of "To one".

After updating the relationship I had to reinstall the app in the simulator, but everything worked properly after that.