A modified Symfony Forms "timezone" type that also displays the timezone offset

TimezoneType.php

<?php
/**
 * A modified version of the original symfony form type that adds the timezone offset.
 * 
 * Original version at:
 * https://github.com/symfony/symfony/blob/2.7/src/Symfony/Component/Form/Extension/Core/Type/TimezoneType.php
 */

/*
 * Installation:
 * =============
 * # services.yml
 * services:
 *     # ...
 *     acme.form.timezone_with_offset:
 *       class: Acme\AcmeBundle\Form\Extension\TimezoneWithOffsetType
 *       tags:
 *         - { name: form.type, alias: acme.form.timezone_with_offset }
 * 
 * Usage:
 * ======
 * $builder
 *     ->add("timezone", \Acme\AcmeBundle\Form\Extension\TimezoneWithOffsetType::class)
 *     // ...
 */

namespace Acme\AcmeBundle\Form\Extension;

use Symfony\Component\Form\ChoiceList\ArrayChoiceList;
use Symfony\Component\Form\Extension\Core\Type\TimezoneType;

/**
 * Class TimezoneWithOffsetType
 */
class TimezoneWithOffsetType extends TimezoneType
{
    /**
     * Timezone loaded choice list.
     *
     * The choices are generated from the ICU function \DateTimeZone::listIdentifiers().
     *
     * @var ArrayChoiceList
     */
    private $choiceList;

    /**
     * {@inheritdoc}
     */
    public function loadChoiceList($value = null)
    {
        if (null !== $this->choiceList) {
            return $this->choiceList;
        }

        return $this->choiceList = new ArrayChoiceList($this->getTimezones(), $value);
    }

    /**
     * Returns a normalized array of timezone choices.
     *
     * @return array The timezone choices
     */
    private static function getTimezones()
    {
        $timezones = array();

        foreach (\DateTimeZone::listIdentifiers() as $timezone) {
            $parts = explode('/', $timezone);

            if (count($parts) > 2) {
                $region = $parts[0];
                $name = $parts[1].' - '.$parts[2];
            } elseif (count($parts) > 1) {
                $region = $parts[0];
                $name = $parts[1];
            } else {
                $region = 'Other';
                $name = $parts[0];
            }

            $dateTime = new \DateTime('now', new \DateTimeZone($timezone));

            $timezones[$region][str_replace('_', ' ', $name) . ' (GMT ' . $dateTime->format('P') . ')'] = $timezone;
        }

        return $timezones;
    }

    /**
     * {@inheritdoc}
     */
    public function getBlockPrefix()
    {
        return 'timezone_with_offset';
    }

}