gistfile1.php

<?php

$xml = new SimpleXMLElement('<sitemap></sitemap>');

foreach ($pages as $page)
    $page_xml = $xml->addChild('page');
    $page_xml->addChild('loc', $page['loc']);
    $page_xml->addChild('priority', $page['priority']);
    $page_xml->addChild('changefreq', $page['changefreq']);
}

$doc = new DOMDocument('1.0','utf-8');
$doc->formatOutput = true;
$domnode = dom_import_simplexml($xml);
$domnode = $doc->importNode($domnode, true);
$domnode = $doc->appendChild($domnode);

echo $doc->saveXML();