mapping model is NULL - core data migration
===

I follow this nice tutorial  http://mipostel.com/index.php/home/70-core-data-migration-standard-migration-part-2 to do my core data migration. 

For some strange reason i always get NULL in the mappingModel in these lines:


 

     NSMappingModel *mappingModel = [NSMappingModel mappingModelFromBundles:nil
                                                                    forSourceModel:sourceModel
                                                                  destinationModel:destinationModel];

(line 191 in the linked code)

I tried to create a very simple derived version of the model, I recreated a mappingModel a 1000 times, made sure that the mapping model file is in the project directory - but this call always returns NULL.

Anybody has an idea what is wrong here?

ps I was just wondering that setting the migration options is called AFTER the mapping Model is used.


       NSURL *storeUrl = [NSURL fileURLWithPath:storePath];   
        NSError *error;   
        NSDictionary *pscOptions = [NSDictionary dictionaryWithObjectsAndKeys:[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
                                    [NSNumber numberWithBool:NO], NSInferMappingModelAutomaticallyOption,
                                    nil];
        
        if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
                                                      configuration:nil
                                                                URL:storeUrl
                                                            options:pscOptions
                                                              error:&error]) {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }   
    
(lines 123...)

**Anyway**

**Why can't the mapping model be found ?**

pss couldn't help holding back :-) this core data migration stuff is much too complicated and difficult compared to doing simple SQL DB migration - wasting soooo much time.

So a BIG THANKS in advance!