PHP中的XML到数组的错误

Question

您好我尝试将XML文件转换为php数组，除此之外，所有节点都会很好。

<category name="Wheels and Tires">
<specification name="Front Tire Type">P245/40R18</specification>
<specification name="Front Wheel Diameter">18.0 x 8.0</specification>
<specification name="Rear Tire Type">P245/40R18</specification>
<specification name="Rear Wheel Diameter">18.0 x 8.0</specification>
</category>

问题是属性名称已从数组中消失，任何想法为什么，谢谢你提前..这里是我的代码和数组结果。

$xml = curl_exec($ch); // $result now contains the response JSON or XML.
$xml_string = simplexml_load_string($xml);
$json = json_encode($xml_string);
$xml_parse = json_decode($json, TRUE);
return($xml_parse);

  array:2 [▼
    "@attributes" => array:1 [▶]
    "specification" => array:4 [▼
      0 => "P245/40R18"
      1 => "18.0 x 8.0"
      2 => "P245/40R18"
      3 => "18.0 x 8.0"
    ]
  ]