index.php

<?php

require __DIR__.'/vendor/autoload.php';

use Symfony\Component\Form\Forms;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\DateType;
use Symfony\Component\Form\Extension\Csrf\CsrfExtension;
use Symfony\Component\HttpFoundation\Session\Session;
use Symfony\Component\Security\Csrf\TokenStorage\SessionTokenStorage;
use Symfony\Component\Security\Csrf\TokenGenerator\UriSafeTokenGenerator;
use Symfony\Component\Security\Csrf\CsrfTokenManager;
use Symfony\Component\Translation\Translator;
use Symfony\Component\Translation\Loader\XliffFileLoader;
use Symfony\Bridge\Twig\Extension\FormExtension;
use Symfony\Bridge\Twig\Extension\TranslationExtension;
use Symfony\Bridge\Twig\Form\TwigRenderer;
use Symfony\Bridge\Twig\Form\TwigRendererEngine;

// create a Session object from the HttpFoundation component
$session = new Session();

$csrfGenerator = new UriSafeTokenGenerator();
$csrfStorage = new SessionTokenStorage($session);
$csrfManager = new CsrfTokenManager($csrfGenerator, $csrfStorage);

// the Twig file that holds all the default markup for rendering forms
// this file comes with TwigBridge
$defaultFormTheme = 'form_div_layout.html.twig';

// the path to TwigBridge library so Twig can locate the
// form_div_layout.html.twig file
$appVariableReflection = new \ReflectionClass('\Symfony\Bridge\Twig\AppVariable');
$vendorTwigBridgeDir = dirname($appVariableReflection->getFileName());
// the path to your other templates
$viewsDir = realpath(__DIR__.'/templates');

$twig = new Twig_Environment(new Twig_Loader_Filesystem(array(
    $viewsDir,
    $vendorTwigBridgeDir.'/Resources/views/Form',
)));
$formEngine = new TwigRendererEngine(array($defaultFormTheme), $twig);
$twig->addRuntimeLoader(new \Twig_FactoryRuntimeLoader(array(
    TwigRenderer::class => function () use ($formEngine, $csrfManager) {
        return new TwigRenderer($formEngine, $csrfManager);
    },
)));

// add the FormExtension to Twig
$twig->addExtension(new FormExtension());

// create the Translator
$translator = new Translator('en');
// somehow load some translations into it
$translator->addLoader('xlf', new XliffFileLoader());
$translator->addResource(
    'xlf',
    __DIR__.'/translations/messages.en.xlf',
    'en'
);

// add the TranslationExtension (gives us trans and transChoice filters)
$twig->addExtension(new TranslationExtension($translator));

// create your form factory as normal
$formFactory = Forms::createFormFactoryBuilder()
    ->addExtension(new CsrfExtension($csrfManager))
    ->getFormFactory();


$form = $formFactory->createBuilder()
    ->add('task', TextType::class)
    ->add('dueDate', DateType::class)
    ->getForm();

var_dump($twig->render('new.html.twig', array(
    'form' => $form->createView(),
)));