如何在PHP中解析复杂的XML-RPC结构？

Here is my XML object: http://pastebin.com/0L8vf0ja Which was created from:

<?xml version="1.0" encoding="utf-8"?>
<methodResponse><params><param><value><struct><member><name>result</name><value><struct><member><name>application_instance_id</name><value><i4>89</i4></value></member></struct></value></member><member><name>status</name><value><i4>0</i4></value></member></struct></value></param></params></methodResponse>

I know upto this level:

 $ApplicationInstanceID = (int)(string)$data->params->param->value->struct->member-> 

But from here, as you see in the pastebin, it becomes an array of objects - and I am not sure how to proceed.

Any ideas, please?

By accessing it as an array:

$x = '<root><child><foo>23</foo><foo>34</foo></child></root>';
$xml = new SimpleXMLElement($x);
var_dump($xml->child->foo[0]);
var_dump($xml->child->foo[1]);

But, if you have it enabled, the xmlrpc_decode function is perhaps easier to use.

var_dump(xmlrpc_decode($yourxml));
array(2) {
  ["result"]=>
  array(1) {
    ["application_instance_id"]=>
    int(89)
  }
  ["status"]=>
  int(0)
}

$ApplicationInstanceID = (int)(string)$data->params->param->value->struct->member[0]-> // first <member>
$ApplicationInstanceID = (int)(string)$data->params->param->value->struct->member[1]-> // second <member>

I'm a bit confused -- it looks like you've already parses the XML into a PHP object... So now just access submembers of the array as you would any elements of an array:

$data->params->param->value->struct->member[0]

And, for it's properties:

$data->params->param->value->struct->member[0]->name

you could try to use xpath to get the node value i think, SimpleXml implements it...
http://php.net/manual/en/simplexmlelement.xpath.php