gistfile1.m

//
// in AppDelegate
//
    // Initialize RestKit Shared Client
    RKObjectManager *objectManager = [RKObjectManager objectManagerWithBaseURLString:_baseURL];
    
    // Enable automatic network activity indicator management
    objectManager.client.requestQueue.showsNetworkActivityIndicatorWhenBusy = YES;
    
    // Initialize object store
    //    NSString *seedDatabaseName = RKDefaultSeedDatabaseFileName;
    NSString *databaseName = @"PSDatabase.sqlite";
    
    RKManagedObjectStore *objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:databaseName];
    //    objectManager.objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:databaseName usingSeedDatabaseName:seedDatabaseName managedObjectModel:nil delegate:self];
    
    /*!
     Map to a target object class -- just as you would for a non-persistent class. The entity is resolved
     for you using the Active Record pattern where the class name corresponds to the entity name within Core Data.
     */
    // User Mapping
    RKManagedObjectMapping *userMapping = [RKManagedObjectMapping mappingForClass:[User class] inManagedObjectStore:objectStore];
    userMapping.primaryKeyAttribute = @"id";
    [userMapping mapKeyPath:@"_id" toAttribute:@"id"];
    [userMapping mapAttributes:@"name", @"email", @"token", @"phoneNumber", @"emailVerified", nil];
    [userMapping mapKeyPath:@"accounts.facebook.userId" toAttribute:@"facebookId"];
    [userMapping mapKeyPath:@"accounts.facebook.token" toAttribute:@"facebookToken"];
    [userMapping mapKeyPath:@"accounts.twitter.userId" toAttribute:@"twitterId"];
    [userMapping mapKeyPath:@"accounts.twitter.token" toAttribute:@"twitterToken"];
    [objectManager.mappingProvider setMapping:userMapping forKeyPath:@"users"];
    [objectManager.mappingProvider setMapping:userMapping forKeyPath:@"user"];
    
    [RKObjectManager sharedManager].serializationMIMEType = RKMIMETypeJSON;
    RKObjectMapping *userSerializationMapping = [userMapping inverseMapping];
    //userSerializationMapping - buildPathIfDoesNotExist
    [objectManager.mappingProvider setSerializationMapping:userSerializationMapping forClass:[User class]];
    
    [objectManager.router routeClass:[NSMutableDictionary class] toResourcePath:@"/users"];
    [objectManager.router routeClass:[User class] toResourcePath:@"/users"];
    
    [RKObjectManager setSharedManager:objectManager];


// in ViewController
// in ViewController
// in ViewController

     User *facebookUser = [NSEntityDescription insertNewObjectForEntityForName:@"User" inManagedObjectContext:self.psDatabase.managedObjectContext.parentContext]; //parent context moves it to diff thread.
    facebookUser.facebookToken = FBSession.activeSession.accessToken;

    [[RKObjectManager sharedManager] postObject:facebookUser usingBlock:^(RKObjectLoader *userLoader){
        NSLog(@"%@", userLoader);
        userLoader.onDidFailWithError = ^(NSError *error){
            //TODO: error modal here, logout of facebook.
            NSLog(@"%@", @"userloader failed.");
        };
        userLoader.onDidLoadObject = ^(id object){
            //facebookUser =
            if (true) {
                NSLog(@"yes");
                // [self performSegueWithIdentifier:@"UserAuthenticated" sender:self];
            }
            else {
                //logout facebook
                NSLog(@"no");
            }
        };
    }];