gistify675384.m

 RKEntityMapping* listMapping = [RKEntityMapping mappingForEntityForName:[FOFSList entityName]
                                                       inManagedObjectStore:objectManager.managedObjectStore];
    [listMapping addAttributeMappingsFromDictionary:@{
                                                         @"id": @"listID",
                                                         @"title": @"name",
                                                         @"description": @"desc",
                                                         @"user": @"user",
                                                         @"following": @"following",
                                                         @"collaborative": @"collaborative",
                                                         @"canonicalUrl": @"canonicalUrl",
                                                         @"venueCount": @"venueCount",
                                                         @"visitedCount": @"visitedCount"
                                                         }];
    
    RKDynamicMapping *dynamicMapping = [RKDynamicMapping new];
    [listMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:nil
                                                                                toKeyPath:@"items"
                                                                              withMapping:dynamicMapping]];

    RKResponseDescriptor *listResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:listMapping
                                                                                             method:RKRequestMethodGET
                                                                                           pathPattern:nil
                                                                                               keyPath:@"response.lists.groups"
                                                                                           statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
    [objectManager addResponseDescriptor:listResponseDescriptor];
    [dynamicMapping setObjectMappingForRepresentationBlock:^RKObjectMapping *(id representation) {
        if ([[representation valueForKey:@"type"] isEqualToString:@"created"]) {
            return listMapping;
        } else if ([[representation valueForKey:@"type"] isEqualToString:@"followed"]) {
            return listMapping;
        }
        
        return nil;
    }];
    
    listMapping.identificationAttributes = @[ @"listID" ];