Get web service response data - objective-c

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 = #"chh#fbr.dk";
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:
Does this trigger a response as soon as the request to the web service?
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.