Question

I have made this so far. It’s code that will make a json String request with an http Header. When i run this code i get no errors. But i get a Expression result unused warning. I should get a response from the web service after sending this http header.

code:

- (void)viewDidLoad
{
    [super viewDidLoad];

    NSString *nid = @"";
    NSString *vocab = @"";
    NSString *inturl = @"testoverview";
    NSString *mail = @"[e-mail]";
    NSString *md5pw = @"4d57e7ef1b7c3f431aca424764e9d786";

    NSDictionary *jsonDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
                                    nid, @"nid", 
                                    vocab, @"vocab",
                                    inturl, @"inturl",
                                    mail, @"mail",
                                    md5pw, @"md5pw",nil];
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:jsonDictionary options:NSJSONWritingPrettyPrinted error:&error];
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

    if (!jsonData) {
        NSLog(@"Got an error; %@", error);
            } else if(jsonData) {

                NSString *url = @"http://www.taenk.dk/services/mobile";
                NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url] cachePolicy:NSURLCacheStorageAllowed timeoutInterval:30.0];

                [request setValue:jsonString forHTTPHeaderField:@"X-FBR-App"];
                [[NSURLConnection alloc] initWithRequest:request delegate:self]; <-- this line triggers the warning: "Expression result unused"

                NSLog(@"jsonString %@", jsonString);

            }

Can anybody clarify 2 things for me:

1. Does this trigger a response as soon as the request to the web service?
2. If yes, how do i print this result out?

Answer 1

You need to assign the result to a variable like

NSURLConnection *con = [[NSURLConnection alloc] initWithRequest:...

for later use (e.g. [con cancel];)

Then you should at least implement the delegate method connection:didFailWithError:. In the class reference I don’t see the connection:didFinishLoading... anymore. Can you use the sendSynchronousRequest:returningResponse:error: instead, then you’ll have the result, be it positive or negative.

This is how I retrieved the data (this version is without ARC):

- (void) connection :(NSURLConnection *)conn didReceiveData :(NSData *)data {
    NSString *msg = [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding];
    [self checkAutoMailReply:msg];
    [msg release];
}

msg contains the pure response data, no header or such.