小程序生成二维码接口B，求教哪里出问题了

遇到的问题就是，返回既没有报错，也没有数据，文档说会返回二进制，转为图片。但现在是什么都没有，不知道哪里出了问题，求助

这是contorller部分

function getIssueQrcodeAction()
            {
                // $issueId     =    $this->request->getPost('issueId');
                $issueId = 2;
                $page     =    'pages/listPage/article/article?issueId=';
                $test = new GetQrcode();
                $t = $test->get_qrcode($page,$issueId);

                print_r($t);
                

            }

这是service业务逻辑处理部分
Class GetQrcode
    {
public function get_qrcode($page,$issueId) {
        header('content-type:image/png');
        $uid = 6;
        $data = array();
        $data['scene'] = $issueId;
        $data['page'] = $page;
        $date['width'] = 450;
        $data = json_encode($data);
        // $access = json_decode($this->get_access_token(),true);
           $a = new WeixinUsers();
        $access_token = $a->access_token();
        $url = "https://api.weixin.qq.com/wxa/getwxacodeunlimit?access_token=".$access_token;
        $da = $this->get_http_array($url,$data);

       return json_encode(array('pictures'=>$da));
        // $this->assign('data',$da);
        // $this->fetch();

    }
    public function get_http_array($url,$post_data) {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
        // curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);   //没有这个会自动输出，不用print_r();也会在后面多个1
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $post_data);
        $output = curl_exec($ch);
        curl_close($ch);
        $out = json_decode($output);
        return $out;
    }
 }

https://mp.weixin.qq.com/debu...

回首忆惘然