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ioscore-datansmanagedobjectcontext

Keeping NSManagedObjects in multiple contexts synchronized

I need an advice for the following scenario. I have two managed object contexts in my app. Depending upon the thread they are accessed via same property i.e.

self.managedObjectContext

If any context changes or saves data i want to keep data sync on both contexts using

-refreshObject:mergeChanges:

and passing mergeChanges = YES, And the app is also listening for notification NSManagedObjectContextDidSaveNotification. But i cannot know which context saved data. (or can i? if yes, Can anybody tell?)

My question is that on receiving this notification should i perform -refreshObject:mergeChanges: on both contexts? e.g.

[bgContext refreshObject:self mergeChanges:YES];
[fgContext refreshObject:self mergeChanges:YES];

OR

[self.managedObjectContext refreshObject:self mergeChanges:YES];

or what approach should i follow?

Solution

  • In your call to NSNotificationCenter -addObserver:selector:name:object:, provide the appropriate MOC as the :object parameter. Now you'll only receive notifications for changes from that MOC. The object: parameter works the same if you're using the blocks-based addObserver:... call.

    You could also use just the notfication, without registering diffferent selecotrs/blocks per context. When the notification arrives, you can check its object property and use that to determine which context needs updating.