如何在XML中为属性创建和设置值

如何在XML中创建和设置属性值？我需要设置ateam id="101"？用这个我列出了我的代码。通过使用createAttribute，我创建了，但我不知道如何设置该属性的值。。

/* create XML Content */
 $domtree = new DOMDocument('1.0', 'UTF-8');
 $xmlRoot = $domtree->createElement("xml");
 $xmlRoot = $domtree->appendChild($xmlRoot);
 $currentTrack = $domtree->createElement("messsage");
 $currentTrack = $xmlRoot->appendChild($currentTrack);
 $currentTrack->appendChild($domtree->createElement('category','Scores'));
 $Game = $currentTrack->appendChild($domtree->createElement('Game',''));
 $Game->appendChild($v = $domtree->createElement('ateam','India'));
 $Game->appendChild($domtree->createElement('score',30));
 $v->appendChild($domtree->createAttribute('id'));
  echo $domtree->saveXML();

输出

<?xml version="1.0" encoding="UTF-8"?>
<xml>
    <messsage>
        <category>Scores</category>
        <Game>
            <ateam id="">India</ateam>
            <score>30</score>
        </Game>
    </messsage>
</xml>

预期输出

 <?xml version="1.0" encoding="UTF-8"?>
    <xml>
        <messsage>
            <category>Scores</category>
            <Game>
                <ateam id="101">India</ateam>
                <score>30</score>
            </Game>
        </messsage>
    </xml>