On Jul 27, 2013, at 9:57 PM, Andy Lee <[email protected]> wrote:
> I'm trying again, this time creating a new NSTimer each time as suggested by
> Scott Ribe. Will let it run a while and see if I notice any drift.
Looks pretty solid after several minutes -- as I would expect. To repeat
Scott's suggestion:
> Personally, I'd probably just do a non-repeating timer, set to fire at the
> next second roll-over. Alloc'ing, scheduling and releasing 1 timer per second
> is not a lot of overhead.
I didn't take my own suggestion to add .001 and it worked fine, though for all
I know it might have a problem once every 10,000 times the app is run.
I stole Rick Mann's code and replaced trunc() with round().
--Andy
==========
@implementation AppDelegate
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
[self _resetTimer];
}
- (void)_resetTimer
{
CFAbsoluteTime fireDateAbs = round(CFAbsoluteTimeGetCurrent() + 0.5); //
Round to the next second
NSDate *fireDate = [NSDate
dateWithTimeIntervalSinceReferenceDate:fireDateAbs];
[[self timer] invalidate];
[self setTimer:[[NSTimer alloc] initWithFireDate:fireDate
interval:1.0
target:self
selector:@selector(_timerDidFire:)
userInfo:nil
repeats:NO]];
[[NSRunLoop currentRunLoop] addTimer:[self timer]
forMode:NSRunLoopCommonModes];
}
- (void)_timerDidFire:(NSTimer *)theTimer
{
[self _updateTimeDisplay];
[self _resetTimer];
}
- (void)_updateTimeDisplay
{
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setTimeStyle:NSDateFormatterMediumStyle];
[dateFormatter setDateStyle:NSDateFormatterNoStyle];
NSString *timeString = [dateFormatter stringFromDate:[NSDate date]];
[[self textField] setStringValue:timeString];
}
@end
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