private function post_type_options()
    {
        $args = array( 'public' => true );
        $post_types = get_post_types($args, 'objects');
        $output = array();
        foreach ($post_types as $post_type) {
            $output[] = array(
                'value' => $post_type->name,
                'label' => $post_type->label
            );
        }
        return $output;
    }