Objective C: http POST request getting Unescaped - ios

Question

I am using a NSMutableURLRequest to send a (synchronous) POST request to a web service.
The request body contains a combination of XML and JSON. Something like :
<element>
<element 2>
<![CDATA[
{"jsondata1":{"datafield1":"data1"},
"jsondata2":"some data"
}
]]>
</element 2>
</element>
the JSON string has been escaped (Using escape() in Javascript)
When I receive the request at the other end I notice that all escaped characters have been unescaped!!
Can anyone tell me why this is happening? And how can I prevent this?
Here is the code that I'm using to send the request:
NSURL *url = [NSURL URLWithString:#"https://my-webservice.com/something.do"];
NSData *xmlResponseDataSave;
NSMutableURLRequest *req = [[NSMutableURLRequest alloc] initWithURL:url];
NSString *msgLength = [NSString stringWithFormat:#"%d",[xmlRequestString length]];
[req addValue:#"application/x-www-form-urlencoded" forHTTPHeaderField:#"Content-Type"];
[req addValue:msgLength forHTTPHeaderField:#"Content-Length"];
[req setHTTPMethod:#"POST"];
NSData *saveData=[xmlRequestString dataUsingEncoding:NSUTF8StringEncoding];
[req setHTTPBody:saveData];
NSError *error=nil;
NSURLResponse *resp=[[NSURLResponse alloc] init];
xmlResponseData=[NSURLConnection sendSynchronousRequest:req returningResponse:&resp error:&error];
NSString *xmlResponseString=[[NSString alloc] initWithData:xmlResponseData encoding:NSUTF8StringEncoding];
Please note: I cannot make any change to the xml or the web service. I can only change the objective c code.

Answer 1

After a lot of trial and error the only solution that I could come up with is to string used in the request body before sending it (Since it's gonna get unescaped while being sent):
xmlRequestString=[xmlRequestString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSData *saveData=[xmlRequestString dataUsingEncoding:NSUTF8StringEncoding];
Though this is not a fix in the truest sense, just a work around. But it works for me (So far).
I'm still clue less about the root cause of the problem and I am still looking for a more elegant solution.