SimpleXMLElement to PHP Array

The $answer can already work as an array. You can do this if you want put it in a real array,

$array = array();
foreach($answer as $k => $v) {
  $array[$k] = $v;
}

In this simple case type casting will also work:

$my_array = (array)$answer

This should work:

$xml = simplexml_load_string($xmlstring);
$json = json_encode($xml);
$array = json_decode($json,TRUE);