On Jul 26, 2013, at 10:36 PM, Scott Ribe <[email protected]> wrote:
> > On Jul 26, 2013, at 7:06 AM, 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(). > > > FYI, in the past, for a quick & dirty solution, I've just set a timer to fire > every 0.1 seconds. Then in the handler you check if the second changed since > the last time, and do nothing if it hasn't. This gets you updating that > appears smooth to the user, unless the main thread spends too much time doing > something and updates don't happen--and that's a problem that's outside the > timers & clocks whose solution is not related to the timers and clocks, whose > solution is of course "don't do that". > > -- > Scott Ribe > [email protected] > http://www.elevated-dev.com/ > (303) 722-0567 voice > Hmm, it's a brute force approach, but certainly easier than understanding mach_time :D I'm using Core Animation for most of the UI changes, so the main thread won't be super busy. I may not even need the 1 second as the seconds won't add a whole lot of info when looking at time in different time zones comparatively, but I want to have this in my tool belt. For the current tool, I could get by fine with a simple hour and minute hand analog clock face. _______________________________________________ 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]
