private function utf8StringSplit($string, $split_length = 1)
{
if (!preg_match('/^[0-9]+$/', $split_length) || $split_length < 1) {
return false;
}
$len = mb_strlen($string, 'UTF-8');
if ($len <= $split_length) {
return array($string);
}
preg_match_all('/.{' . $split_length . '}|[^\\x00]{1,' . $split_length . '}$/us', $string, $ar);
return $ar[0];
}