Contrary to other notes posted here, SimpleXML *DOES NOT* properly handle non-UTF8 encoded XML documents.
A proper "iso-8859-1" declared and encoded XML document will not parse with SimpleXML for PHP 5.2.17 or 5.5.1 when using extended characters (that is, byte values greater than 127)
DOMDocument, on the other hand, will correctly parse incoming iso-8859-1 XML documents and can also be used to perform character translation to UTF8:
$dom = new DOMDocument();
if($dom->loadXML($fileContents)){ // $fileContents is an XML document with iso-8859-1 encoding specified in the declaration
$dom->encoding = 'utf-8'; // convert document encoding to UTF8
return $dom->saveXML(); // return valid, utf8-encoded XML
