dispatch_queue_t downloadQueue = dispatch_queue_create("downloader", NULL);

        dispatch_async(downloadQueue, ^{
            NSData *result = self.envoyerLaDemande;
            dispatch_async(dispatch_get_main_queue(), ^{

                id strResult=nil;

                strResult = [NSJSONSerialization JSONObjectWithData:result options:0 error:nil];

                NSLog(@"strResult: %@", strResult);

                NSString* boolOk=[strResult objectForKey:@"result"];
                NSLog(@"BoolOk: %@", boolOk);

$data = array();

if(condition == 1)
{
$data["result"] = "ok";
}
else
{
$data["result"] = "error";
}
$data["result"] = "coucou";
}
echo json_encode($data);