具有相同元标记值PHP的多个标记

Question

$keywords = explode(',', $this->find_metatag_value('article:tag', $page_code));
        foreach ($keywords as $keyword)
        {
            $keyword = trim($keyword);
            if ($keyword != '')
            {
                $result->add_tag($keyword);
            }
        }

This code is working but there is multiple tags with same metatag value. I want grab all tags

Its only grab first article:tag

From:

<meta property="article:tag" content="som text"/>
<meta property="article:tag" content="some text1"/>
<meta property="article:tag" content="latest text"/>
<meta property="article:tag" content="text line2"/>
<meta property="article:tag" content="some textdd"/>