Get Value of an XML (XSD) with PHP

After searching and searching I did not get a good method. However, use my common sense and using str_replace from php remove all the code that was in my way ( XSD ), leaving only the binary file to decode and show. Then I leave the code that gave solution so that it can be consulted by another person!

$pdf = str_replace('<xs:schema xmlns:mstns="http://tempuri.org/dsPDFGuia.xsd" xmlns="http://tempuri.org/dsPDFGuia.xsd" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" id="dsPDFGuia" targetNamespace="http://tempuri.org/dsPDFGuia.xsd" attributeFormDefault="qualified" elementFormDefault="qualified"><xs:element name="dsPDFGuia" msdata:IsDataSet="true" msdata:UseCurrentLocale="true"><xs:complexType><xs:choice minOccurs="0" maxOccurs="unbounded"><xs:element name="Guia"><xs:complexType><xs:sequence><xs:element name="Inicial" type="xs:long" minOccurs="0"/><xs:element name="Final" type="xs:long" minOccurs="0"/><xs:element name="BytesImagen" type="xs:base64Binary" minOccurs="0"/></xs:sequence></xs:complexType></xs:element></xs:choice></xs:complexType></xs:element></xs:schema><diffgr:diffgram xmlns:msdata="urn:schemas-microsoft-com:xml-msdata" xmlns:diffgr="urn:schemas-microsoft-com:xml-diffgram-v1"><dsPDFGuia xmlns="http://tempuri.org/dsPDFGuia.xsd"><Guia diffgr:id="Guia1" msdata:rowOrder="0"><Inicial></Inicial><Final></Final><BytesImagen>',"",$pdf);
$pdf = str_replace('</BytesImagen></Guia></dsPDFGuia></diffgr:diffgram>',"",$pdf);

header('Content-type: application/pdf');
echo base64_decode($pdf);

Without having information about your code or the service, I can think of two possible solutions, the first is using regular expressions and preg_match () :

$xml = /* Aquí va tu XML */;

$xmlData = preg_match("/(?s)(?<=\<bytesimagen\>)(.*?)(?=\<\/bytesimagen\>)/", $xml, $matchesXML);

$b64 = array_pop($matchesXML); // Este es el valor que necesitas

The next option is to use simplexml_load_string () and it's more correct but you should correct the XML that you expose since it returns error, indicating that there is extra content that should not be there.

$xml = /* Aquí va tu XML */;

$xmlData = json_decode(json_encode(simplexml_load_string($xml)), 1);

$b64 = $xmlData['dspdfguia']['guia']['bytesimagen']; // Este es el valor que necesitas