Track real time usage on Cocoa app
Inspired by @PeterHosey's interesting comment on this question , I decided to implement a time tracking system.
how
- Application starts, counter starts
- The application ends, the entire duration is logged
- At any time (even during runtime) that the total usage time exceeds the allowed time, the user is notified
However, I have a couple ... conceptual problems:
- What will I track? Is it enough
[NSDate date]
? - What if the user just changes their system date / time at some point?
- Also, what specific methods of the delegate should be hooked up? I mean, where would you call the start / stop routines for the counting functions?
I'm all ears! :-)
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1 answer
Well, I don't think you need to use [NSDate date] for this. Why aren't you using the mach_absolute_time () function? To track the elapsed time, it can be some kind of timer (ticks, for example, every minute).
GCD timers are a simple flexible way to implement timers that you can pause and resume if needed (for example, if you want to pause it while the program is not in use.).
- (void)createTimerSource
{
// myTimerQueue and trialTimer are class members
myTimerQueue = dispatch_queue_create("label.yourapp.com", NULL);
trialTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, myTimerQueue);
dispatch_source_set_timer(m_ping_timer, dispatch_time(DISPATCH_TIME_NOW,TimerPeriod * NSEC_PER_MSEC), TimerPeriod * NSEC_PER_MSEC,NSEC_PER_SEC/10);
// set event handler
dispatch_source_set_event_handler(m_ping_timer,^{
// the code to check time elapsed
});
// set the cancel handler
dispatch_source_set_cancel_handler(m_ping_timer,^{
// release timer dispatch source
if(trialTimer)
dispatch_release(trialTimer);
// release dispatch timer
if(myTimerQueue)
dispatch_release(myTimerQueue);
});
// created sources always suspended
dispatch_resume(trialTimer); // to suspend the timer use dispatch_suspend(trialTimer)
}
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