$pdfView = new ViewModel();
# When the action can be found at:
# MyModule/MyController/mypdf
# the path to the according template would be:
# my-module/my-controller/mypdf
$pdfView->setTemplate('my-module/my-controller/mypdf');
$pdfView->setVariables(array(
    'somevar' => $somevar,
));
$pdfRenderer = $this->getServiceLocator()->get('ViewPdfRenderer');
$html = $pdfRenderer->getHtmlRenderer()->render($pdfView);
$pdfEngine = $pdfRenderer->getEngine();

$pdfEngine->load_html($html);
$pdfEngine->render();
$pdfContent = $pdfEngine->output();

# make sure to create public/pdf before
file_put_contents(getcwd().'/public/pdf/mypdf.pdf', $pdfContent);