NSMutableURLRequest *urlRequest = [NSMutableURLRequest requestWithURL:
                                              [NSURL URLWithString:@""]];

NSString *username = @"username";
NSString *password = @"password";

NSString *format = [NSString stringWithFormat:@"%@:%@", username, password];

      [urlRequest addValue:[NSString
          stringWithFormat:@"Basic %@", [format base64Encoding]]
        forHTTPHeaderField:@"Authorization"];

NSError *error;
NSURLResponse *response;

NSData *data = [NSURLConnection sendSynchronousRequest:urlRequest
                                     returningResponse:&response
                                                 error:&error];

NSString *stringFromASC = [NSString UTF8String:[data bytes]
length:[data length]];