Explanation of UTF-8 header testing for Symfony / Swift Mailer

gistfile1.php

<?php
$expectedHeaderMessage = Swift_Message::newInstance()
	->setSubject('Información')
	->setCharset('utf-8')
;

$msgString = $expectedHeaderMessage->toString();

/*
echo $msgString: 
Message-ID: <1295950012.4d3ea0bcbcb3a@swift.generated>
Date: Tue, 25 Jan 2011 10:06:52 +0000
Subject: =?utf-8?Q?Informaci=C3=B3n?=
From: 
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
*/

gistfile2.php

<?php
$matches = array();

$pattern = '/\nSubject: ([A-z0-9\-\?\= ]*).*\n/';

preg_match($pattern, $msgString, $matches);

gistfile3.php

<?php
$browser->
	info("The UTF-8 header is as we expect it to be")->
	with('mailer')->begin()->
		checkHeader('Subject', '/'.preg_quote($matches[1]).'/')->
	end()
;