Dreaming of promise base API for event handling

LoginViewController.m

- (id)init 
{
	if (self = [super initNibName:nil bundle:nil]) {
		[[self whenViewDidLoad] then:^{

			id loginPromise = [client login:self.loginField password:self.passwordField when:[self.loginButton whenTouchDown]];
			[UIAlertView presentMessage:^{ return [loginPromise alertError]; } when:[loginPromise whenFail]];
			[client saveAccessToken:[self.loginPromise whenSuccess]];
			[self presentModalViewController:[RegisterViewController willCreate] when:[self.registerButton whenTouchDown]];
		}];
	}
	return self;
}