Small questions about PHP DOMDocument

PHP DOMDocument has a small problem. how does PHP & nbsp; DOMDocument insert data before the root node? For example, if I want to insert: & lt; urlset & nbsp; xmlns = "http://www.sitemaps.org/schemas/sitemap/0.9" & gt; before & lt; root & gt;, the result is: PHP DOMDocument encountered a small problem.
PHP DOMDocument
How to insert data before the root node?
For example Insert before:


Result:



Title

Share To: insert before:
------解决方案--------------------
urlset也算是一个节点，你创建了这个节点，然后找哪个父节点去append？