Home/ Questions/Q 6942941
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-27T13:05:28+00:00

My app uses a UIManagedDocument to handle its data with Core Data. There’s a

  • 0

My app uses a UIManagedDocument to handle its data with Core Data. There’s a to-many relationship between 2 entities: Post and Tag.

When I want to edit a post, I create a temporary NSManagedObjectContext, set its parentContext to the UIManagedDocument’s managedObjectContext, and retrieve the post using the objectWithID: method.

Let’s assume this:

  • MOC1 is the UIManagedDocument’s NSManagedObjectContext
  • MOC2 is the temporary NSManagedObjectContext to edit the post
  • post1 is the post in MOC1
  • post2 is the post in MOC2

Here’s the problem:

  • post1.tags returns 2 tags
  • post2.tags returns 0 tags

All of post2 properties are properly retrieved, except for the to-many relationship tags.

Why does post2.tags have no tag?

Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    I wish I had an answer for this, but so far as I’ve been able to determine, it’s a bug. To-many relationship retrieval just doesn’t seem work at all in this scenario.

    Frankly, it seems a bit hard to believe this would have escaped testing, but I’ve been completely unable to make this work in any way.

    • 0