Reordering array attributes then save back to XML in php

I have this XML:

  <picture id="2">
    <title>B</title>
  </picture>
  <picture id="3">
    <title>C</title>
  </picture>
  <picture id="0">
    <title>A</title>
  </picture>

Trying to achieve this:

  <picture id="1">
    <title>B</title>
  </picture>
  <picture id="2">
    <title>C</title>
  </picture>
  <picture id="0">
    <title>A</title>
  </picture>

Using this to get a list of ‘id’ attribute values:

$objXML = new SimpleXMLElement(XML_FILE_NAME, null, true);
$picture = $objXML->xpath('picture');
$arrayCurrent = array();
foreach($picture as $value) {
    $arrayCurrent[] = (string)$value['id'];
}
sort($arrayCurrent); // put XML into numerical 'id' order
print_r($arrayCurrent);

It returns: Array ( [0] => 0 [1] => 2 [2] => 3 ) Any ideas how to re-index like so: 0, 1, 2 and save the appropriate ‘id’ attributes back to their correct positions in the XML doc?

Thanks, Andy