how to validate login username and password for Sharepoint using sharepoint web service from ios?

i am using sharepoint webservice for an ipad application. i am sending the credentials required to login to the sha开发者_如何转开发repoint along with the SOAP request. but the problem is when i send wrong username or password it the web service does not throw up any authentication error. instead it gives an html error page as a response. how to validate login credentials?

You try checking the http response code for that error page. Are you using NSURL... or ASIHTTP, etc? Here's how you get ot the headers in NSHTTPURLResponse:

NSHTTPURLResponse *r = (NSHTTPURLResponse*)response;
NSDictionary *dict = [r allHeaderFields];