yii2导出csv文件乱码怎么办

/**
 * 导出csv
 * @author yhdsir
 * @param array    $parameter header 表头
 * @param array    $parameter data   数据
 * @param string   $filename         导出名字
 */
public function export($parameter, $filename = '')
{
    if (empty($filename)) {
        $filename = date('Y-m-d_H-i-s');
    }

    $filename = str_replace(array('"', "'", ' ', ','), '_', $filename) . '.csv';

    if (is_array($parameter)) {
        header('Content-Type: application/vnd.ms-excel');
        header('Cache-Control: max-age=0');
        header("Content-Disposition: attachment;filename={$filename}");
        $fp = fopen('php://output', 'w');
        //fwrite($fp, chr(0xEF) . chr(0xBB) . chr(0xBF));  // 添加 BOM
        if (!empty($parameter['header']) && is_array($parameter['header'])) {
            foreach ($parameter['header'] as $i => $v) {
                // CSV的Excel支持GBK编码，一定要转换，否则乱码 
                // $head[$i] = iconv('utf-8', 'gbk', $v); 
                $parameter['header'][$i] = iconv('utf-8', 'gb2312//TRANSLIT//IGNORE', $v);
            }
            // 将数据通过fputcsv写到文件句柄 
            fputcsv($fp, $parameter['header']);
        }
        if (isset($parameter['data'])) {
            foreach ($parameter['data'] as $row) {
                foreach ($row as $i => $v) {
                    $row[$i] = iconv('utf-8', 'gb2312//TRANSLIT//IGNORE', $v);
                }
                fputcsv($fp, $row);
            }
        }
        fclose($fp);

        return true;
    }
    throw new \yii\web\HttpException(500, "Not a valid parameter!");
}

iconv ( string $in_charset , string $out_charset , string $str ) : string