Convert ISO-8859-2 characters into UTF-8

Question

I am looking for an regex to convert ISO-8859-2 characters into UTF-8 characters...Is there some function to do this?

I have tried the following method:

public function convertCharacters($string)
    {
        $unPretty = array('/ä/', '/ö/', '/ü/', '/Ä/', '/Ö/', '/Ü/', '/ß/',
            '/ą/', '/Ą/', '/ć/', '/Ć/', '/ę/', '/Ę/', '/ł/', '/Ł/' ,'/ń/', '/Ń/', '/ó/', '/Ó/', '/ś/', '/Ś/', '/ź/', '/Ź/', '/ż/', '/Ż/',
            '/Š/','/Ž/','/š/','/ž/','/Ÿ/','/Ŕ/','/Á/','/Â/','/Ă/','/Ä/','/Ĺ/','/Ç/','/Č/','/É/','/Ę/','/Ë/','/Ě/','/Í/','/Î/','/Ď/','/Ń/',
            '/Ň/','/Ó/','/Ô/','/Ő/','/Ö/','/Ř/','/Ů/','/Ú/','/Ű/','/Ü/','/Ý/','/ŕ/','/á/','/â/','/ă/','/ä/','/ĺ/','/ç/','/č/','/é/','/ę/',
            '/ë/','/ě/','/í/','/î/','/ď/','/ń/','/ň/','/ó/','/ô/','/ő/','/ö/','/ř/','/ů/','/ú/','/ű/','/ü/','/ý/','/˙/',
            '/Ţ/','/ţ/','/Đ/','/đ/','/ß/','/Œ/','/œ/','/Ć/','/ć/','/ľ/');

        $pretty   = array('ae', 'oe', 'ue', 'Ae', 'Oe', 'Ue', 'ss',
            'a', 'A', 'c', 'C', 'e', 'E', 'l', 'L', 'n', 'N', 'o', 'O', 's', 'S', 'z', 'Z', 'z', 'Z',
            'S','Z','s','z','Y','A','A','A','A','A','A','C','E','E','E','E','I','I','I','I','N',
            'O','O','O','O','O','O','U','U','U','U','Y','a','a','a','a','a','a','c','e','e','e',
            'e','i','i','i','i','n','o','o','o','o','o','o','u','u','u','u','y','y',
            'TH','th','DH','dh','ss','OE','oe','AE','ae','u');

        $permalink = strtolower(preg_replace($unPretty, $pretty, $string));

        return  str_replace(" ", "-", preg_replace("/[^a-zA-Z0-9 ]/", "", $permalink) );
    }

But it doesn't work, it changes wrong characters.