On Jul 26, 2013, at 12:09 PM, Ken Thomases <[email protected]> wrote:
> On Jul 25, 2013, at 9:26 PM, [email protected] wrote: > >> Yep, I know of these, but this is tied to the run loop and timers on the >> runloop can be delayed. >> The reason I went with dispatch_timer is because it can be done with its own >> thread and if I understand correctly, frees it from the runloop... >> >> _timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, >> >> dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0UL)); >> dispatch_source_set_timer(_timer, dispatch_walltime(NULL, 0), >> >> (unsigned)(delayInSeconds * NSEC_PER_SEC), 0); >> dispatch_source_set_event_handler(_timer, ^{ >> // Get updated time here. >> dispatch_async(dispatch_get_main_queue(), ^{ >> // Talk back to main thread here. >> }); >> }); > > Since you're updating the GUI, you're tied to the responsiveness of the main > thread's run loop, anyway. The dispatch to the main queue in the code above > is conceptually similar to having a timer fire on the main thread's run loop. > > 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 ? _______________________________________________ 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]
