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 yiiwebHttpException(500, "Not a valid parameter!");
}

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