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Today I was playing with Core Data technology and I was trying to check whether it is possible to update the store schema according to the changes I made to the entities, relationships and whatever else.

I found out that the important steps are:

• Use the versioning: before modifying your current schema you should select “Editor -> Add Model Version..”
• Edit as much as you like
• Select the new version as the active one
• Go to your app delegate file and modify the - (NSPersistentStoreCoordinator *) persistentStoreCoordinator method as follows:

  NSURL *url = [applicationFilesDirectory URLByAppendingPathComponent:@"YourApp.storedata"];
      __persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:mom];
  
  NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
  						 [NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
  						 [NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
  
  if (![__persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:url options:options error:&error]) {
  		// The rest of the code here
  	}
  
  return __persistentStoreCoordinator;
  

  
  
  The highlighted lines are the one to be added. Please notice that row 8 needs to be updated with options:options. I only tried it using NSSQLiteStoreType as persistent store type but it should work fine even with NSXMLStoreType.

References:

1. Working with Core Data: Schema Versioning and Lightweight Migrations