Problem parsing a soap response (iphone / touchxml)

I make a webservice and it works, the problem is with the webservice response. I have this xml (and i want to parse with touchxml), the problem is with touchxml that it founds two xml, one inside the other and it make crash. Here is my question, how i can parse this xml? how i can remove all the stuff like soap-env, xmlns ....

<?xml version="1.0" encoding="ISO-8859-1"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"><SOAP-ENV:Body>
<ns1:getCategoriesResponse xmlns:开发者_如何学运维ns1="http://192.168.1.30/wyws/server.php"><return xsi:type="xsd:string">

    <?xml version="1.0" encoding="UTF-8"?>
    <categories>
       <category id="1" desc="Encontrar Códigos " icon="wy">Código </category>
       <category id="3" desc="" icon="farm">Far</category>
       <category id="5" desc="" icon="gas">Gas</category>
       <category id="6" desc="" icon="hos">Hos</category>
       <category id="7" desc="" icon="pol">Pol</category>
    </categories>

</return></ns1:getCategoriesResponse></SOAP-ENV:Body></SOAP-ENV:Envelope>

This is how i make the call:

NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];
NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]];
[theRequest addValue:@"8bit" forHTTPHeaderField:@"Content-Transfer-Encoding"];
[theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
[theRequest addValue: @"getCategories" forHTTPHeaderField:@"SOAPAction"];

[theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"];
[theRequest setHTTPMethod:@"POST"];
[theRequest setHTTPBody:[soapMessage dataUsingEncoding:NSUTF8StringEncoding]];  

NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self]; 

webData = [[NSMutableData data] retain];

And then

-(void)connectionDidFinishLoading:(NSURLConnection *)connection
{

    NSLog(@"DONE. Received Bytes: %d", [webData length]);

    NSString *theXML = [[NSString alloc] initWithBytes: [webData mutableBytes] length:[webData length] encoding:NSISOLatin1StringEncoding];


NSLog(theXml);
....
}

I wrote this, it´s not very elegant, but it works.

 NSRange in = [tmpTheXml rangeOfString:@"<return xsi:type=\"xsd:string\">"];
 NSRange fi = [tmpTheXml rangeOfString:@"</return>"];
 int inic = in.location + in.length;
 NSRange tmprange = {inic,fi.location - inic} ;
 tmpTheXml = [tmpTheXml substringWithRange:tmprange];