Does UIManagedDocument handle conflcts

Question

Does UIManagedDocument handle row level conflcts for me or do I need to handle those, and his answer was it does handle row level conflicts. Maybe I misunderstood him but I am not seeing this.

So I am going to ask a few key questions in hopes of getting some clarification here, again this is UIManagedDocument

If I have a table Author having first and last name fields what happens if: A) I have a row with author: 'Jon Do' - it has sync'd to two devices. Then I edit the first name on one device from 'Jon' to 'John' and edit the last name on the other device from 'Do' to 'Doe'. How will iCloud and UIManagedDocument handle this? Will I get some sort of a notification that I need to respond to in order to handle the conflict? I tried the following code but I never get the notificiation:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_ondocumentStateChangedNotification:) name:UIDocumentStateChangedNotification object:self.openedDoc];

B) What if I add a different author to the two devices so that there are now two rows to be merged will UIManagedDocument handle that for me or do I need to do something myself? If I need to do something myself what do I need to do? I tried signing up for the NSPersistentStoreDidImportUbiquitousContentChangesNotification but that doesn't ever seem to come through for me either. Which context do I sign up against? I tried this:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(_onPersistentStoreDidImportUbiquitousContentChanges:) name:NSPersistentStoreDidImportUbiquitousContentChangesNotificationobject:self.openedCaddy.managedObjectContext.parentContext];

Also do I need to handle the NSManagedObjectContextDidSaveNotification myself for a UIManagedDocument or does UIManagedDocument handle that for me?

Any and all help is greatly appreciated I am really struggling here. I adopted iCloud and UIManagedDocument at the launch of iOS 5 and fumbled my way though the lack of documentaiton then but managed to ship a product but now I want iCloud to really work not simply do a winner takes all approach to document sync.

Answer 1

I figured it out. UIManagedDocument does handle row level conflicts.

The reason I never saw any name:NSPersistentStoreDidImportUbiquitousContentChangesNotificationobject notifications is because I was not setting the moc's persistent store options properly. To get core data to start syncing you have to set at a minimum the following options: NSPersistentStoreUbiquitousContentNameKey & NSPersistentStoreUbiquitousContentURLKey.

When I first started using iCloud 2 years ago I always assumed that the call to setUbiquitous:itemAtURL:destinationURL:error: did this for me and was equivalent but it's not. setUbiquitous:itemAtURL:destinationURL:error: simply tells iCloud to sync the files at that URL, it does nothing with core data - think dropbox. To get the core data portion of UIManagedDocument to sync those two options need to be set.

I have started a github repo that clarifies some of this and makes getting up and running with UIManagedDocument much easier. http://github.com/dtrotzjr/APManagedDocument

Hopefully this helps someone else. I feel rather dumb not realizing this sooner but when I first implemented iCloud sync for iOS 5 2 years ago the documentation was sparse and iCloud didn't work very well so I assumed my behavior was normal.