What are the ways to get data from the global queue besides the Notification center?

Question

Objective-C

For example, in order for the controller to receive data by calling the model's "getData" method (shown below), I use the Notification center, which publishes the received data in the notification to which the given controller is subscribed.
I would like to know: are there any alternative options for getting data by the controller from the global queue?
Thank you!

- (void)getData {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@""]];
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"%@", error.description);
        } else {
            NSError *parsingError;
            NSDictionary *parsedData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&parsingError];
            if (parsingError) {
                    NSLog(@"Error while parsing data %@", parsingError.description);
            } else {
                dispatch_async(dispatch_get_main_queue(), ^{
                    ;
    NSURLSession *session = [NSURLSession sharedSession];
    NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
        if (error) {
            NSLog(@"%@", error.description);
        } else {
            NSError *parsingError;
            NSDictionary *parsedData = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&parsingError];
            if (parsingError) {
                    NSLog(@"Error while parsing data %@", parsingError.description);
            } else {
                dispatch_async(dispatch_get_main_queue(), ^{
                    if (completionBlock){
                       completionBlock(parsedData);
                   }
                });
            }
        }
    }];
    [task resume];
}

The call looks like this

[self getData:^(id result){
    //process
}];

Yes, you, in fact, use this method yourself in NSURLSession. In order to avoid callback hell, you can look towards PromiseKit
Another, almost forgotten way, through delegates...