core data migration xcode 4.2 is not update the data for app already available in app store

Question

we are using core data for our online catalog and its working fine and app available in app store now I need to upgrade the core date with some of fields and attributes. It

Answer 1

You need to use data migration technique. I faced the similiar task a while back.
There are tutorial out there on this. Data migration.

Answer 2

I've now found out that this is quite simple - once you know where to look.# In my AppDelegate I set-up the NSPersistentStoreCoordinator - and you need to add some options to this to tell it to handle auto-migrate:

    NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:

    [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,

    [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];

    NSError *error;
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];

    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType        configuration:nil URL:storeUrl options:options error:&error]) {
          // Handle error
        NSLog(@"Problem with PersistentStoreCoordinator: %@",error);
    }

Then you need to do in xCode:

1.  Select your xcdatamodeld file
2.  Select the Editor Menu at the top - then choose Add Model Version
3.  Now your xcdatamodeld file have two (modelname.xcdatamodel & modelname2.xcdatamodel ) .
4.  Now modelname.xcdatamodel  have the green check mark implies it is current version, but we need to change the modelname2.xcdatamodel as a current version
5.  Select the xcdatamodeld file and then select the View Menu at the top - then Choose Utilities - then Choose the Show File Inspector is shown in right side of Xcode and then Select the Versioned Core Data Model - have Current(DropDownList) - select modelname2(the one you just made current version have green check mark).
6.  Now when you install this version onto a device that has the old model - it will automatically upgrade that model to the new model.

This seems great and as simple as I wanted - but I think you need to be careful during development as you change a model - otherwise you will have to create a new version for each change.

I think what I will do is that I will keep all of the changed files and then once I get ready to deploy my update I'll delete all the in-between files and just deploy with the oldest and latest models.