gistfile1.m

@interface GCDCoalescent : NSObject
- (void)dispatchOn:(dispatch_queue_t)queue after:(double)seconds block:(dispatch_block_t)block;
@end


@implementation GCDCoalescent
{
    uint64_t count;
}

- (void)dispatchOn:(dispatch_queue_t)queue after:(double)seconds block:(dispatch_block_t)block;
{
	uint64_t eventNumber = __sync_add_and_fetch(&count, 1);
	dispatch_after(dispatch_time(DISPATCH_TIME_NOW, seconds * NSEC_PER_SEC), queue, ^{
		if (count > eventNumber) return;
		block();
	});
}

@end