Transform XML contained in a string into json

Hello, I need to transform an XML contained in a string into json Object. How do I do that? I've tried some native PHP functions without success.

<?xml version="1.0" encoding="UTF-8"?>
<UDSObjectList>
<UDSObject>
<Handle>chg:445700</Handle>
<Attributes>
<Attribute DataType="2005">
<AttrName>status</AttrName>
<AttrValue>APR</AttrValue>
</Attribute>
</Attributes>
</UDSObjectList>
</UDSObject>
<UDSObjectList>
</xml>

ANSWER:

Use the following function to solve the problem:

public function XMLtoArray($XML)
    {
        $xml_parser = xml_parser_create();
        xml_parse_into_struct($xml_parser, $XML, $vals);
        xml_parser_free($xml_parser);
        // wyznaczamy tablice z powtarzajacymi sie tagami na tym samym poziomie
        $_tmp='';
        foreach ($vals as $xml_elem) {
            $x_tag=$xml_elem['tag'];
            $x_level=$xml_elem['level'];
            $x_type=$xml_elem['type'];
            if ($x_level!=1 && $x_type == 'close') {
                if (isset($multi_key[$x_tag][$x_level]))
                    $multi_key[$x_tag][$x_level]=1;
                else
                    $multi_key[$x_tag][$x_level]=0;
            }
            if ($x_level!=1 && $x_type == 'complete') {
                if ($_tmp==$x_tag)
                    $multi_key[$x_tag][$x_level]=1;
                $_tmp=$x_tag;
            }
        }
        // jedziemy po tablicy
        foreach ($vals as $xml_elem) {
            $x_tag=$xml_elem['tag'];
            $x_level=$xml_elem['level'];
            $x_type=$xml_elem['type'];
            if ($x_type == 'open')
                $level[$x_level] = $x_tag;
            $start_level = 1;
            $php_stmt = '$xml_array';
            if ($x_type=='close' && $x_level!=1)
                $multi_key[$x_tag][$x_level]++;
            while ($start_level < $x_level) {
                $php_stmt .= '[$level['.$start_level.']]';
                if (isset($multi_key[$level[$start_level]][$start_level]) && $multi_key[$level[$start_level]][$start_level])
                    $php_stmt .= '['.($multi_key[$level[$start_level]][$start_level]-1).']';
                $start_level++;
            }
            $add='';
            if (isset($multi_key[$x_tag][$x_level]) && $multi_key[$x_tag][$x_level] && ($x_type=='open' || $x_type=='complete')) {
                if (!isset($multi_key2[$x_tag][$x_level]))
                    $multi_key2[$x_tag][$x_level]=0;
                else
                    $multi_key2[$x_tag][$x_level]++;
                $add='['.$multi_key2[$x_tag][$x_level].']';
            }
            if (isset($xml_elem['value']) && trim($xml_elem['value'])!='' && !array_key_exists('attributes', $xml_elem)) {
                if ($x_type == 'open')
                    $php_stmt_main=$php_stmt.'[$x_type]'.$add.'[\'content\'] = $xml_elem[\'value\'];';
                else
                    $php_stmt_main=$php_stmt.'[$x_tag]'.$add.' = $xml_elem[\'value\'];';
                eval($php_stmt_main);
            }
            if (array_key_exists('attributes', $xml_elem)) {
                if (isset($xml_elem['value'])) {
                    $php_stmt_main=$php_stmt.'[$x_tag]'.$add.'[\'content\'] = $xml_elem[\'value\'];';
                    eval($php_stmt_main);
                }
                foreach ($xml_elem['attributes'] as $key=>$value) {
                    $php_stmt_att=$php_stmt.'[$x_tag]'.$add.'[$key] = $value;';
                    eval($php_stmt_att);
                }
            }
        }
        return $xml_array;
    }