问题
I have two entities (MetaData and Prices) with a many-to-many relationship. The entity MetaData has an attribute dataIsInvalid to invalidate all related prices in the entity Price. I'm using a NSFetchedResultsController for MetaData and one FRC for Price.
The predicate for FRC Price is @"ANY metaData.dataIsInvalid == 0". Of course, if I change the dataIsInvalid attribute in MetaData, the controllerDidChangeContent method from FRC Price is not called, but the method in FRC MetaData. So I want to reload the FRC Price data in the controllerDidChangeContent method from FRC MetaData.
The problem is, that the FRC Price cannot see the changes in MetaData at that time. So that doesn't work.
What is the best practice for this scenario? Should I use NSNotificationCenterwith NSManagedObjectContextDidSaveNotification? This will be called after saveToPersistentStore and the FRC Price can see the changes.
Thanks for Help.
来源：https://stackoverflow.com/questions/25914904/nsfetchedresultscontroller-notify-for-changes-in-another-entity-best-practice