example

 RKEntityMapping *mapping = [RKEntityMapping mappingForEntityForName:@"conversation" inManagedObjectStore:managedObjectStore];


    mapping.identificationAttributes = @[@"identifier"];
    [mapping addAttributeMappingsFromDictionary:@{
            @"@metadata.identifier" : @"identifier"
    }];

    [mapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"members" toKeyPath:@"otherUsers" withMapping:[self profileObjectMapping:managedObjectStore]]];