Reputation: 7876
I'm struggling with core data... I don't understand some things so if someone could help me, I would be very grateful! I have an entity (Recipe) with a relationship to-many with another one (Meal). I would like to select all the recipes which have no connection with a meal... so I've tried:
Code:
[myRecipes filteredSetUsingPredicate:[NSPredicate predicateWithFormat:@"meal=%@", nil]];
But it doesn't work... it crashes.
When I look at the SQL database under recipe I don't see meal (I think it's because it's a to-many relationship). How can I make it?
Thanks
Upvotes: 1
Views: 1099
Reputation: 27900
According to this question
To test for an empty relationship you should compare the count of the to-many key to zero.
For example,
[NSPredicate predicateWithFormat:@"meal.@count == 0"]
Upvotes: 6