private function build_content($article, $bundles = array(), $meta = array()) { $bundles = array_unique($bundles); $content = ''; // Add custom meta for request. $meta = apply_filters('apple_news_api_post_meta', $meta); if (!empty($meta['data']) && is_array($meta['data'])) { $content .= $this->mime_builder->add_metadata($meta); } $content .= $this->mime_builder->add_json_string('my_article', 'article.json', $article); foreach ($bundles as $bundle) { $content .= $this->mime_builder->add_content_from_file($bundle); } $content .= $this->mime_builder->close(); return $content; }