XMLWriter

In your code implementation, the class autoloader looks for the XMLWriter class in the app/Models directory.
This class is not in the catalog, or it does not have an App\Models namespace defined.

not enough information

There is no class autoloader in CI < 4, so you couldn't load the class simply by writing $xml = new XMLWriter();

that is the way in which i'm trying to load it, as if i was loading the PHP extension, but it is not working, i don't know why CI4 thinks that i'm trying to use a CI4's class, i already reviewed the extension in the server and it looks like that extension is enabled and running, any help/hint will be appreciated, thanks.

try

PHP Code:

$xml = new \XMLWriter();