Send multiple NSURLSession

Question

I have an NSURLSession that looks like this, and what I want to do, is if no data is returned then I want it to try again and again, for up to lets say 8 seconds or 3 attempts and then if still nothing is there, I will have it return no data. Here is what I have now,

NSURLSession *session = [NSURLSession sharedSession];
[[session dataTaskWithURL:[NSURL URLWithString:urlIn] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
// handle response
    //use my data
    // if no data I want to try again?


}] resume];

So I want it to either try 3 times or until 8 seconds has passed. How could I go about doing this,

Thanks for the help in advance.

Answer 1

Okay so I am almost there I just have a little bit more to work out with timer. Here is what I have.

I got properties

NSInteger attemptInt;
NSInteger _counter;
NSDate *date = [NSDate date];

And then these two methods for my timer

- (void)startCountdown
{
    _counter = 8;

    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1
                                                      target:self
                                                    selector:@selector(countdownTimer:)
                                                    userInfo:nil
                                                     repeats:YES];
}

- (void)countdownTimer:(NSTimer *)timer
{
    _counter--;
    if (_counter <= 0) {
        [timer invalidate];
        NSLog(@"8 sec passed");
    }
}

And then here is where I am getting my data.

- (void)getMenuItems:(NSString*)urlIn{
    NSURLSession *session = [NSURLSession sharedSession];
    [[session dataTaskWithURL:[NSURL URLWithString:urlIn] completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
    //One problem I am facing is I have to call timer for main thread
   if ([date timeIntervalSinceNow] <= 8 && [response expectedContentLength] == 0) {
        attemptInt++;
        [self getMenuItems:url];
    }
    if (attemptInt >= 3) {
        NSLog(@"NO DATA");
    }
    else if ([response expectedContentLength] == 0) {
        NSLog(@"TRY AGAIN");
        attemptInt++;
        [self getMenuItems:url];
    }
    else {
        //GOT MY DATA :)
        self.mealdata=[[MealData alloc]init:data];
    }

So I got the attempts worked out am a timer set up I just need some help finishing up to check whether 8 seconds has passed first?