Steps taken: 1. Added Data Model version: Changed my XXX.xcdatamodel to XXX.xcdatamodeId with Design -> Data Model -> Add Model Version.

1. Set the new XXX 2.xcdatamodel as current version

2. Added an attribute to XXX 2.xcdatamodel

3. Added NSMigratePersistentStoresAutomaticallyOption and NSInferMappingModelAutomaticallyOption

   • like most tutorials, I added the option in the addPersistentStoreWithType.

ran the code and I got this error:

Unresolved error Error Domain=NSCocoaErrorDomain Code=134130 UserInfo=0x146bb80 "Operation could not be completed. (Cocoa error 134130.)", { URL = file://localhost/Users/tleung/Library/Application%20Support/iPhone%20Simulator/3.0/Applications/B585CDFC-17C3-4A44-84E2-0B75893C46B8/Documents/favorites.sqlite; metadata = { NSPersistenceFrameworkVersion = 241; NSStoreModelVersionHashes = { City = <70ea1f9f aaa9af29 52d2bfe4 3071d97f 8224f765 d69928d5 e5844120 52742a35>; StationStore = <40d8093a 1d7d00ec 178b4374 36dfc137 ccfa3a88 87e2d467 69e8ae7e d4c49dbb>; }; NSStoreModelVersionHashesVersion = 3; NSStoreModelVersionIdentifiers = ( ); NSStoreType = SQLite; NSStoreUUID = "9DD342A6-1F68-4997-A097-096DC96D7BF3"; }; reason = "Can't find model for source store"; }

I've also tried

NSString *path = [[NSBundle mainBundle] pathForResource:@"YOURDB" ofType:@"momd"];
  NSURL *momURL = [NSURL fileURLWithPath:path];
  managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:momURL];

as suggested by other posts with no success. It seems that it can't find ANY of my models... anyone have any idea?