CodeIgniter多个文件上传 - 唯一文件名

I made a function which is successfully uploading [multiple] the files. But If I try to change the filename, the filename is getting changed but only last selected file is getting uploaded.

Here is my code.

<?php
    $files = $_FILES['userfile'];
    $dir = './uploads/';
    foreach ($files['name'] as $key => $value) {
        $direction = $dir . $_FILES['userfile']['name'][$key];
        move_uploaded_file($_FILES['userfile']['tmp_name'][$key], $direction);
    }
?>

Manage to do this

       $files = $_FILES['userfile'];
        $dir = './uploads/';
        foreach ($files['name'] as $key => $value) {

            $filename = $_FILES["userfile"]["name"][$key];

            $temp = explode(".", $filename);
            $newfilename = uniqid('',true).'.'.end($temp);
            $direction = $dir.$newfilename; 
            move_uploaded_file($_FILES['userfile']['tmp_name'][$key], $direction);
        }

problem was with the microtime()

Try This Code

//load date helper 
$this->load->helper('date');

$files = $_FILES['userfile'];
        $dir = './uploads/';
        foreach ($files['name'] as $key => $value) {

            $filename = $_FILES["userfile"]["name"][$key];

            $temp = explode(".", $filename);
            //
            $file_tempname = date('Y-m-d H:i:s');
            //
            $newfilename = $file_tempname.'.'.end($temp);

            $direction = $dir.$newfilename; 
            move_uploaded_file($_FILES['userfile']['tmp_name'][$key], $direction);
        }