gistfile1.txt

  RKManagedObjectMapping *postMapping = [RKManagedObjectMapping mappingForEntityWithName:@"MRNPost"];

  postMapping.primaryKeyAttribute = @"postID";
  [postMapping mapKeyPath:@"id"         toAttribute:@"postID"];
  [postMapping mapKeyPath:@"url"        toAttribute:@"url"];
  [postMapping mapKeyPath:@"content"    toAttribute:@"content"];
  [postMapping mapKeyPath:@"created_at" toAttribute:@"createdAt"];
  [postMapping mapKeyPath:@"updated_at" toAttribute:@"updatedAt"];
  [postMapping mapKeyPath:@"images"     toRelationship:@"images" withObjectMapping:postImageMapping];