Renders a TYPO3 Fluid StandaloneView respecting the given language. Can be used from the TYPO3 backend context (e.g. scheduler task)

StandaloneViewService.php

/**
 * Renders a Fluid StandaloneView respecting the given language
 *
 * @param string $language The language (e.g. de, dk or se)
 * @return string
 * @throws \TYPO3\CMS\Extbase\Configuration\Exception\InvalidConfigurationTypeException
 */
public function renderStandaloneView($language = '') {

	if ($language !== '') {
		// Temporary set Language of current BE user to given language
		$GLOBALS['BE_USER']->uc['lang'] = $language;
	}

	/** @var \TYPO3\CMS\Fluid\View\StandaloneView $view */
	$view = $this->objectManager->get('TYPO3\\CMS\\Fluid\\View\\StandaloneView');
	$view->setFormat('html');
	$extbaseFrameworkConfiguration = $this->configurationManager->getConfiguration(ConfigurationManagerInterface::CONFIGURATION_TYPE_FULL_TYPOSCRIPT);
	$templateRootPath = GeneralUtility::getFileAbsFileName($extbaseFrameworkConfiguration['plugin.']['tx_standaloneview.']['view.']['templateRootPath']);
	$view->setTemplatePathAndFilename($templateRootPath . 'StandaloneView.html');

	// Set Extension name, so localizations for extension get respected
	$extensionKey = 'standaloneview';
	$view->getRequest()->setControllerExtensionName(GeneralUtility::underscoredToUpperCamelCase($extensionKey));

	return $view->render();
}