//LoginViewController.m
- (IBAction)loginButtonPress:(id)sender {
    (...)
   [[LoginSession sharedInstance] authenticateUser:[username text] withPassword:[password text] andDomain:[domain text]];
}


//LoginSession.m
- (void) authenticateUser:(NSString *)userName withPassword:(NSString *)password andDomain:(NSString *)domain{
    (...)
     RKRequest * loginRequest = [[RKClient sharedClient] get:@"/login" queryParameters:loginData delegate:self];
    (...)
}

//LoginSession.m
- (void)request:(RKRequest *)request didLoadResponse:(RKResponse *)response;

//LoginSession.m
UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle: nil];

LoginViewController *loginViewController =
(LoginViewController *)[mainStoryboard instantiateViewControllerWithIdentifier: @"loginViewController"];

//LoginSession.m
@property (strong, retain) LoginViewController *loginViewController;

//LoginSession.h
@property (strong, retain) LoginViewController *loginViewController;

@synthesize loginViewController;

UIStoryboard *mainStoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle: nil];
loginViewController =
(LoginViewController *)[mainStoryboard instantiateViewControllerWithIdentifier: @"loginViewController"];