CodeIgniter で複数のファイルをアップロードする際の「アップロードするファイルが選択されていません」エラーを解決する方法

private function upload_files($path, $title, $files)
{
    $config = array(
        'upload_path'   => $path,
        'allowed_types' => 'jpg|gif|png',
        'overwrite'     => 1,
    );

    $this->load->library('upload', $config);

    $images = array();

    foreach ($files['name'] as $key => $image) {
        $_FILES['images[]']['name']      = $files['name'][$key];
        $_FILES['images[]']['type']      = $files['type'][$key];
        $_FILES['images[]']['tmp_name']  = $files['tmp_name'][$key];
        $_FILES['images[]']['error']     = $files['error'][$key];
        $_FILES['images[]']['size']      = $files['size'][$key];

        $fileName = $title . '_' . $image;

        $images[] = $fileName;

        $config['file_name'] = $fileName;

        $this->upload->initialize($config);

        if ($this->upload->do_upload('images[]')) {
            $this->upload->data();
        } else {
            return false;
        }
    }

    return $images;
}