$indexModel = new IndexModel;
  $indexModel->responseMsg($postObj);

<?php
     class IndexModel extends Model{
         public function responseMsg($postObj){
              $toUser    =  $postObj->FromUserName;
             $FromUser  =  $postObj->ToUserName;
             $time      =  time();
             $MsgType   =  'news';
             $arr       =  array(
                             array(
                                'title'=>'百度',
                                'Description'=>'百度非常棒',
                                'PicUrl'=>'https://ss0.bdstatic.com/5aV1bjqh_Q23odCf/static/superman/img/logo/bd_logo1_31bdc765.png',
                                'Url'=>'https://www.baidu.com/',
                                 ),
                              array(
                                'title'=>'腾讯',
                                'Description'=>'qq非常棒',
                                'PicUrl'=>'http://img3.redocn.com/20130821/20130817_2bc2c708243ecd0f59ccqU6c3AgCIYt1.jpg',
                                'Url'=>'http://www.qq.com/',
                                 ),
                               array(
                                'title'=>'hao123',
                                'Description'=>'hao123非常好',
                                'PicUrl'=>'http://img1.imgtn.bdimg.com/it/u=2829392212,3986743237&fm=21&gp=0.jpg',
                                'Url'=>'https://www.hao123.com/',
                                 ),
                         );
                 $template  =  "<xml>
                                    <ToUserName><![CDATA[%s]]></ToUserName>
                                    <FromUserName><![CDATA[%s]]></FromUserName>
                                    <CreateTime>%s</CreateTime>
                                    <MsgType><![CDATA[%s]]></MsgType>
                                    <ArticleCount>".count($arr)."</ArticleCount>
                                    <Articles>";
                    foreach ($arr as $k => $v) {
                      $template .=  "<item>
                                    <Title><![CDATA[".$v['title']."]]></Title> 
                                    <Description><![CDATA[".$v['Description']."]]></Description>
                                    <PicUrl><![CDATA[".$v['PicUrl']."]]></PicUrl>
                                    <Url><![CDATA[".$v['Url']."]]></Url>
                                    </item>";
                    }
                     $template  .= "</Articles>
                                   </xml>";
                    $info        =  sprintf($template,$toUser,$FromUser,$time,$MsgType);
                    echo   $info;
         }
     }