小程序生成二維碼接口B，求教哪里出問題了

遇到的問題就是，返回既沒有報錯，也沒有數(shù)據(jù)，文檔說會返回二進(jìn)制，轉(zhuǎn)為圖片。但現(xiàn)在是什么都沒有，不知道哪里出了問題，求助

這是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);
                

            }

這是service業(yè)務(wù)邏輯處理部分
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($ch, CURLOPT_RETURNTRANSFER, 1);   //沒有這個會自動輸出，不用print_r();也會在后面多個1
        curl_setopt($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...