Core Data - Default Migration ( Manual )

Question

i\'ve read all possible blogs and SO post on the subject - but still not sure what\'s going on. I\'ve also read this but still no luck - their guide to Default migration kin

Answer 1

With the help i got from this question i got to solve your issue.

I have put together a demo app based on the default master/detail template with core data. When run it first time, make sure you have the "TestData" model selected in "TestData.xcdatamodeld". Add some rows, then move to "TestData 2.xcdatamodel" and the migration will make the proper changes.

The demo app can be downloaded from here

Answer 2

If you didn't find answer i can suggest small trick. First, idk why this happens but source model, destination model and mapping model have different values of versionHashes for same entities.

i programmaticaly corrected them and migration happens.

 NSURL *fileURL = [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"cdm"];
 NSMappingModel *mappingModel = [[NSMappingModel alloc] initWithContentsOfURL:fileURL];

 NSArray *newEntityMappings = [NSArray arrayWithArray:mappingModel.entityMappings];
 for (NSEntityMapping *entityMapping in newEntityMappings) {

[entityMapping setSourceEntityVersionHash:[sourceModel.entityVersionHashesByName     valueForKey:entityMapping.sourceEntityName]];
[entityMapping setDestinationEntityVersionHash:[destinationModel.entityVersionHashesByName valueForKey:entityMapping.destinationEntityName]];
        }
mappingModel.entityMappings = newEntityMappings;

        BOOL ok = [migrationManager migrateStoreFromURL:sourceStoreURL
                                                   type:sourceStoreType
                                                options:nil
                                       withMappingModel:mappingModel
                                       toDestinationURL:destinationStoreURL
                                        destinationType:destinationStoreType
                                     destinationOptions:nil
                                                  error:&error];