On Jul 26, 2013, at 10:06 PM, Ken Thomases <[email protected]> wrote:
> On Jul 25, 2013, at 11:37 PM, [email protected] wrote: > >> On Jul 26, 2013, at 12:09 PM, Ken Thomases <[email protected]> wrote: >> >>> Also, the above code doesn't adjust the timer to fire on the second as Rick >>> suggested. You're asking it to fire every so many seconds (delayInSeconds) >>> but you aren't specifying when during the second to fire. Rather than >>> passing 0 as the second parameter of dispatch_walltime(), you should >>> compute an adjustment to try to get close to a whole second. Since >>> dispatch_walltime() uses gettimeofday() when you pass NULL for the first >>> parameter, I'd use that same call to fill in a timeval structure and then >>> pass NSEC_PER_SEC - (tp.tv_usec * NSEC_PER_USEC) as the second parameter. >>> >>> Regards, >>> Ken >>> >> Thanks Ken, no I hadn't yet bothered to do this, as dispatch_walltime() was >> initially close enough to work on the other bits of the app. >> It would make a difference to reduce some lag. >> What is the part in the second parameter your are doing there… >>> NSEC_PER_SEC - (tp.tv_usec * NSEC_PER_USEC) >> Looks like something to adust it but what is tp.tv_usec ? > > I hypothesized a struct timeval variable named "tp" that you passed to > gettimeofday(). Then you would use the sub-second part (the tv_usec field) > to figure out roughly how far off of a whole second dispatch_walltime() would > be when passed NULL for the first parameter, since it will also use > gettimeofday(). > > Regards, > Ken > Ok yes, that much kind of made sense. But I'm not clear how I can know the delta from the whole second before it begins firing. (Honestly I've gotten my head a bit turned around by mach_time) I'm going to have to spend some time to understand this I think. _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
