问题
I'm currently looking into CoreData and need to save multiple values per key. In my case I just need to save a couple of strings, max 9, for a single Key in CoreData.
Specifically, I want to save players for a game. My game object already contains relationship objects to these players, but I also want to save the Player names as records on the game object itself, as players can be deleted by my users and I want my game objects to be immune for that.
I know in Cloudkit you can set the value of a certain key to e.g. "set of strings", and this can be done in CoreData relationships to when creating a one-to-many relationship. I was wondering if there is a by-the-book way to do this in regular CoreData key-value pairs as well.
回答1:
It's easier to think about CoreData as objects rather than low-level data storage. It's not really designed as a key/value system (except in the sense that any object's properties can be thought of as a dictionary).
For the example you give, it might be more in keeping with CoreData's object persistence style to flag deleted players as unavailable rather than removing them, so that your history remains intact.
回答2:
You could use an attribute of type Transformable to store your set. NSArray and NSSet conform to NSCoding so CoreData can take care of all data transforming, archiving and unarchiving for you.
来源：https://stackoverflow.com/questions/35434861/save-multiple-values-per-key-in-coredata