Core Data - Best way to save a "number of items"

Question

The user will have a static list of items to choose from. Using a Picker View they will choose one of the items and then select how many of them they want.

Whats the best way to save this in core data? A Struct?

struct order {
    NSInteger item;
    NSInteger numberOf;
};

Or some sort of relationship?

Many Thanks

Answer 1

In Core Data you would create an entity to model the users choices.

Assuming the item is just a name then you would have an entity something like this:

ChoiceEntity{
    itemName=string;
    quantity=int;
}

If items have their own entity, it would look like this:

ChoiceEntity{
    quantity=int;
    item <<--(required,nullify)--> ItemEntity;
}

ItemEntity {
    // ... attributes of items. 
    choices <--(optional, cascade)-->> ChoiceEntity;
}

For simple data without relationships, you can think of Core Data entities as simple structs. (In fact, under the hood, that's what they are.)