protected function createController($controller)
    {
        if (false === strpos($controller, '::')) {
            throw new \InvalidArgumentException(sprintf('Unable to find controller "%s".', $controller));
        }

        list($class, $method) = explode('::', $controller, 2);

        if ($this->container->has($class)) {
            $controller = $this->container->get($class);
        } else {
            if ( ! class_exists($class)) {
                throw new \InvalidArgumentException(sprintf('Class "%s" does not exist.', $class));
            }

            $controller = new $class();
        }

        if ($controller instanceof ContainerAwareInterface) {
            $controller->setContainer($this->container);
        }

        return array($controller, $method);
    }