gerar_xml.php

// Gera o arquivo XML do sitemap
$xml = '<?xml version="1.0" encoding="UTF-8"?>
<urlset
    xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.sitemaps.org/schemas/sitemap/0.9
    http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd">
    <url>
        <loc>'.HOME.'</loc>
        <lastmod>'.$date.'</lastmod>
        <changefreq>weekly</changefreq>
        <priority>1.00</priority>
    </url>';
    foreach($rows as $v){
        $datetime = new DateTime($v['updated_at']);
        $date = $datetime->format(DateTime::ATOM);
        $xml .='
        <url>
            <loc>'.HOME.'/'.$v['slug'].'</loc>
            <lastmod>'.$date.'</lastmod>
            <changefreq>weekly</changefreq>
            <priority>0.85</priority>
        </url>';
    }
$xml .= '
</urlset>';