core/helpers/StringHelper.php
public static function mb_str_split($string, $length = 1)
    {
        $array = [];
        $stringLength = mb_strlen($string, 'UTF-8');
    
        for ($i = 0; $i < $stringLength; $i += $length) {
            $array[] = mb_substr($string, $i, $length, 'UTF-8');
        }
    
        return $array;
    }
public static function mb_str_split($string, $length = 1)
    {
        $array = [];
        $stringLength = mb_strlen($string, 'UTF-8');
    
        for ($i = 0; $i < $stringLength; $i += $length) {
            $array[] = mb_substr($string, $i, $length, 'UTF-8');
        }
    
        return $array;
    }
public static function mb_str_split ( $ string , $ length = 1 ) { $ array = [ ] ; $ stringLength = mb_strlen ( $ string , 'UTF-8' ) ; for ( $ i = 0 ; $ i < $ stringLength ; $ i += $ length ) { $ array [ ] = mb_substr ( $ string , $ i , $ length , 'UTF-8' ) ; } return $ array ; }
Multibyte-safe str_split funciton.

@param string $string The string to split into an array
@param integer $length The length of the chars to cut.
@since 1.0.12
Multibyte - safe str_split funciton .