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Editorial Team
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Asked: 2026-06-07T02:34:43+00:00

I have three contexts: masterMOC – private queue tied to the persistent store, so

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I have three contexts:

masterMOC - private queue tied to the persistent store, so physical saves happen here
----mainMOC - main queue tied to the UI, child of masterMOC
-------backgroundMOC - private queue, child of mainMOC

Let’s see I create an Employee object on the mainMOC, then save the mainMOC. Then I save the masterMOC (which writes to disk).

Now, I’ve saved the Employee NSManagedObjectID in a variable, objectID. I want to get this Employee on the backgroundMOC. Does [backgroundMOC objectWithId:objectID] serve this purpose? Will it go to the persistent store and fetch this object using that method? Or will I have to preform a fetch request?

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1 Answer

  1. Editorial Team

    Your’e doing it right. They want you to pass objects between MOContexts using ID’s. objectWithId will hit the persistent store and load the object in a fresh state.
    The only gotcha you have to worry about is this case.

    You fetch an object or create a new object in a MOContext.
    You try pass the objectID to another context WITHOUT SAVING
    The new MOContext wont know about the updates, and if you created a new object the objectID wouldn’t be in the persistent store, so I think it returns nil or it’s not defined.

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