SimpleXML을 사용하여 사용자 정의 네임스페이스의 요소에 어떻게 액세스할 수 있습니까?

<code class="xml"><?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:moshtix="http://www.moshtix.com.au">
  <channel>
    <link>qweqwe</link>
    <moshtix:genre>asdasd</moshtix:genre>
  </channel>
</rss></code>

<code class="php">$rss = simplexml_load_string($xmlString);

foreach ($rss->channel as $channel) {
    echo 'link: ', $channel->link, "\n";
    echo 'genre: ', $channel->children('moshtix', true)->genre, "\n";
}</code>

link: qweqwe
genre: asdasd