ios里边的身份验证在webservice里面应该怎样写才能获取用户名密码

ios里面的身份验证在webservice里面应该怎样写才能获取用户名密码
比如:
NSURL *url = [NSURL URLWithString:@"http://www.dreamingwish.com/"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setUseKeychainPersistence:YES];
[request setUsername:@"username"];
[request setPassword:@"password"];

这里设置了用户名密码
webservise  在哪里获取

------解决方案--------------------
webService里的代码我不知道怎么写。。
你看看你IOS里POST的代码吧

NSString *soapMessage =@"xxxxxxxxxx";
	
    NSURL *url = [NSURL URLWithString:CMCC_ANTENNA_URL];
    NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];
    NSString *msgLength = [NSString stringWithFormat:@"%d", [soapMessage length]];
	
    [theRequest addValue: @"text/xml; charset=utf-8" forHTTPHeaderField:@"Content-Type"];
    [theRequest addValue: FIND_ACTION forHTTPHeaderField:@"SOAPAction"];
    [theRequest addValue: msgLength forHTTPHeaderField:@"Content-Length"];
    [theRequest setHTTPMethod:@"POST"];
    [theRequest setHTTPBody: [soapMessage dataUsingEncoding:NSUTF8StringEncoding]];
	
    NSURLConnection *theConnection = [[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
	
    if( theConnection )
    {
		webData = [[NSMutableData data] retain];
    }
    else
    {
        NSLog(@"theConnection is NULL");
    }

------解决方案--------------------
呃。。。你不知道怎么组合request字符串吗？

NSString *str = [NSString stringWithFormat:
                     @"<?xml version=\"1.0\" encoding=\"utf-8\"?>\
                     <soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\">\
                     <soap:Body>\
                     <Login xmlns=\"http://tempuri.org/\">\
                     <userName>%@</userName>\
                     <password>%@</password>\
                     </Login>\
                     </soap:Body>\
                     </soap:Envelope>", username, password];