PHP Sitemap Nasıl Oluşturulur?

<?php

$export = '<?xml version="1.0" encoding="UTF-8"?>';
$export .= "\n";
$export .= '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:image="http://www.google.com/schemas/sitemap-image/1.1">';
$export .= "\n";
$export .= "<url>\n";
.....
foreach ($sayfalar as $sayfa)                
{
$export .= "<url>\n";
$export .= " <loc><![CDATA[".$sayfaLinki."]]></loc>\n";
$export .= " <lastmod>".$dateNow."</lastmod>\n";
$export .= " <changefreq>weekly</changefreq>\n";
$export .= " <priority>0.80</priority>\n";
$export .= "</url>\n";
}
.....
$export .= "</url>\n";

$export.="</urlset>";


header('Content-type: application/xml');
    echo $export;