Setting one-to-many relationship Core Data and Magical Record

问题

If I have a Conversation entity with a one-to-many relationship to Messages (i.e. one conversation can have many messages) and I create a new message entity like so:

_message = [Message MR_createInContext:_managedObjectContext];
_message set properties ...

// Use this method to set relationship?
[_conversation addToMessageObject:(Message *)] 

If I already have a _conversation object, how do I add this new message to the conversation (in other words, how do I establish the relationship)?

回答1:

I've had a problem with this too, you need to create the relationship on the _message instead:

_message.conversation = _conversation;

来源：https://stackoverflow.com/questions/22274428/setting-one-to-many-relationship-core-data-and-magical-record