How to return XML in a Zend Framework application

Question

I'm having problems returning XML in my ZF application. My code:

class ProjectsController extends Gid_Controller_Action
{
    public function xmlAction ()
    {
        $content = "<?xml version='1.0'><foo>bar</foo>";
        header('Content-Type: text/xml');
        echo $content;
    }
}

I've also tried the following:

class ProjectsController extends Gid_Controller_Action
{
    public function xmlAction ()
    {
        $content = "<?xml version='1.0'><foo>bar</foo>";
        $this->getResponse()->clearHeaders();
        $this->getResponse()->setheader('Content-Type', 'text/xml');
        $this->getResponse()->setBody($content);
        $this->getResponse()->sendResponse();
    }
}

Could someone point me in the right direction how to achieve this?