ModelBundle/Document/Site.php
public function getAliasIdForLanguage($language)
    {
        /** @var ReadSiteAliasInterface $alias */
        foreach ($this->aliases as $key => $alias) {
            if ($alias->getLanguage() == $language) {
                return $key;
            }
        }

        return null;
    }
public function getAliasIdForLanguage($language)
    {
        /** @var ReadSiteAliasInterface $alias */
        foreach ($this->aliases as $key => $alias) {
            if ($alias->getLanguage() == $language) {
                return $key;
            }
        }

        return null;
    }
Return alias id for given language

@param string $language

@return int