Copying NSManagedObjects Between NSManagedObjectContext Instances

- (NSManagedObject*)copyObject:(NSManagedObject*)object
                     toContext:(NSManagedObjectContext*)moc
                        parent:(NSString*)parentEntity;
{
  NSString *entityName = [[object entity] name];

  NSManagedObject *newObject = [NSEntityDescription
                                insertNewObjectForEntityForName:entityName
                                inManagedObjectContext:moc];
  [[self lookup] setObject:newObject forKey:[object objectID]];

  NSArray *attKeys = [[[object entity] attributesByName] allKeys];
  NSDictionary *attributes = [object dictionaryWithValuesForKeys:attKeys];

  [newObject setValuesForKeysWithDictionary:attributes];

  id oldDestObject = nil;
  id temp = nil;
  NSDictionary *relationships = [[object entity] relationshipsByName];
  for (NSString *key in [relationships allKeys]) {

    NSRelationshipDescription *desc = [relationships valueForKey:key];
    NSString *destEntityName = [[desc destinationEntity] name];
    if ([destEntityName isEqualToString:parentEntity]) continue;

    if ([desc isToMany]) {

      NSMutableSet *newDestSet = [NSMutableSet set];

      for (oldDestObject in [object valueForKey:key]) {
        temp = [[self lookup] objectForKey:[oldDestObject objectID]];
        if (!temp) {
          temp = [self copyObject:oldDestObject
                        toContext:moc
                           parent:entityName];
        }
        [newDestSet addObject:temp];
      }

      [newObject setValue:newDestSet forKey:key];

    } else {
      oldDestObject = [object valueForKey:key];
      if (!oldDestObject) continue;

      temp = [[self lookup] objectForKey:[oldDestObject objectID]];
      if (!temp && ![destEntityName isEqualToString:parentEntity]) {
        temp = [self copyObject:oldDestObject
                      toContext:moc
                         parent:entityName];
      }

      [newObject setValue:temp forKey:key];
    }
  }

  return newObject;
}