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I'm working on an App that uses a persistent store to save and retreive data. I have it all working, but there is some curious behavior that makes me doubt very much if what I'm doing is correct.

When I build my App, some values are loaded into the persistent store and can be accessed. This remains true when I close the App in the interface builder and then reload it.

The loaded data, when logged, looks shortly like:

entity: Appointment; data: { day = monday; hours = 8; project = project1; task = task1; }

Now, when rebuilding the App, the entries in the store are still present, however, the data that should be in those entries appears to be destroyed.

The loaded data now looks like:

entity: Appointment; data: fault

I would assume that either the store is rebuilt entirely and thus no entries would remain, or it would stay intact as it was before rebuilding.

An appointment is of NSManagedObject class defined in my xcdatamodel, and has four string attributes (day, hours, project and task).

Lorenzo B
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eelco
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2 Answers2

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Without the code it's difficult to see what is going on. Did you receive an error?

data:fault does not mean you do something wrong. Each time you do a request, Core Data does not retrieve the whole object but a skeleton of it. Data within the object are not populated immediately but only when you fire a fault (e.g. accessing a property of that entity).

So, if you log that object in this manner:

NSLog(@"%@", managedObject);

this could be the motivation of that.

For further info about faulting I suggest you to read Faulting.

Hope it helps.

Lorenzo B
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  1. Run your simulator, then in top menu bar, choose iOS Simulator -> Reset Content & Settings.... It'll reset all data for your App, including CoreData.

  2. Or your can go to ~/Library/Application\ Support/iPhone\ Simulator/5.0/Applications, delete the App bundle.

  3. Or just delete the xxx.sqlite file in ~/Library/Application\ Support/iPhone\ Simulator/5.0/Applications/E88E378D-14A9-4900-A613-BF9082D4B2C1(YourAppBundle)/Documents/.

Then rebuild your project and run it, clean data now. ;)

Kjuly
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  • Does this mean that the above is normal behavior then? Deleting the App from the simulator already helped me clear the data, but I was assuming I did something wrong. – eelco May 14 '12 at 13:28
  • @eelco ya, I think so. As the file exists, so the next time you rebuild your project, the `if (! [fileManager fileExistsAtPath:storePath]) {}` (in `persistentStoreCoordinator` method of AppDelegate.m) part will be passed. – Kjuly May 14 '12 at 13:35
  • Ok, I'll rest assured then. If you could edit your answer so it states that this is indeed default behavior I will mark it as the correct answer. – eelco May 14 '12 at 13:50
  • @eelco never mind, besides, I'm not totally sure about it. Maybe there's a more accurate answer. ;) – Kjuly May 14 '12 at 15:36