GCD: How to remove waiting tasks from serial queue?

Question

First I create a serial queue like this

static dispatch_queue_t queue = dispatch_queue_create(\"myQueue\", DISPATCH_QUEUE_SERIAL);

then, at som

Answer 1

With Davids answer getting me on track I succeeded in doing this like so

taskCounter++;
dispatch_async(queue, ^{
    if (taskCounter > 1) {
        taskCounter--;
        NSLog(@"%@", @"skip");
        return;
    }
    NSLog(@"%@", @"start");
    // do stuff
    sleep(3);
    taskCounter--;
    NSLog(@"%@", @"done");
});

taskCounter has to be either an ivar or a property (initialize it with 0). In that case it doesn't even need the __block attribute.