Formatting string received by JSON

Question

In my app I need to parse JSON objects received from a remote server, not administered by me. What my app is getting from the server is a JSON string, that I convert to a NSDictionary. Then I am trying to retrieve the value of some of the JSON objects. At this point I am facing the following issue: I will take as example the value for the key "current_latitude: that I am retrieving.

If I make a NSLog with the retrieved string, I get this on my console:

VALUE=(
    "-12.19061989"
)

Obviously, when I try to convert this string to a double, the app crashes.

This is the code so far:

NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData
        options:NSJSONReadingMutableContainers
        error:&jsonError];


for (NSString* key in json) {
       id value = [json objectForKey:key];
       NSLog(@"VALUE=%@",[value valueForKey:@"current_latitude"]);
       NSLog(@"VALUE=%@",[value valueForKey:@"current_longitude"]);
}

What should I do to get a normal string?

Thank you

EDITED

This is the complete piece of code to make the JSON request:

//  request para descargar la posicion de los vehiculos disponibles

    NSString *latitud = self.deviceLat;

    NSString *longitud = self.deviceLon;

    NSLog (@"latitud actual =%@",latitud);
    NSLog (@"longitud actual =%@",longitud);



    NSURL *apiURL = [NSURL URLWithString:
                     [NSString stringWithFormat:@"http://hidden here/?current_latitude=%@&current_longitude=%@", latitud,longitud]];
    NSURLRequest *request = [NSURLRequest requestWithURL:apiURL]; // this is using GET, for POST examples see the other answers here on this page
    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                               if(data.length) {
                                   NSString *responseString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                                   if(responseString && responseString.length) {
                                       NSLog(@"dATOS RECIBIDOS=%@", responseString);
                                       NSError *jsonError;
                                       NSData *objectData = [responseString dataUsingEncoding:NSUTF8StringEncoding];
                                       NSDictionary *json = [NSJSONSerialization JSONObjectWithData:objectData
                                                                                            options:NSJSONReadingMutableContainers
                                                                                              error:&jsonError];



                                       for (NSString* key in json) {
                                           id value = [json objectForKey:key];
                                           // do stuff
                                           NSLog(@"VALUE=%@",[value valueForKey:@"current_latitude"]);
                                           NSLog(@"VALUE=%@",[value valueForKey:@"current_longitude"]);


                                           //ponemos en el punto deseado un marcador de tipo PinDisponible
                                           NSString *latstring = [value valueForKey:@"current_latitude"];
                                           NSString *lonstring = [value valueForKey:@"current_longitude"];

                                           NSLog(@"LATITUD=%@", latstring);
                                           NSLog(@"LONGITUD=%@", lonstring);

                                           //double latdouble = [latstring doubleValue];
                                           //double londouble = [lonstring doubleValue];

                                           //NSLog(@"latdouble: %f", latdouble);

                                           //NSLog(@"londouble: %f", londouble);

                                           //CLLocationCoordinate2D vehiculo = [mapView centerCoordinate];
                                           //vehiculo.latitude = latdouble;
                                           //vehiculo.longitude = londouble;

                                           //PinDisponible *vehiculoDisponible = [[PinDisponible alloc] initWithTitle:@"Vehiculo disponible" location:vehiculo];
                                       //    [self.mapView addAnnotation:vehiculoDisponible];
                                       }


                                   }
                               }
                           }];
}

Answer 1

Well, that's because it's not a string... it's an array with a string (the parenthesis you see at the logs are part of arrays desciption), so I guess you could just grab

[[value valueForKey:@"current_latitude"] firstObject]

if you're positive that this is what you get from the backend. I hope that this makes sense