title: Listening to change to current week?
body: <p>I'm testing a few things for my self in OS X, and I would like to know what the best way to do this would be.</p>
  
  <p>I have a method, that returns the current week number.</p>
  
  <pre><code>-(NSInteger) getWeekNumber {
    NSDate *date = [NSDate date];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components:NSWeekCalendarUnit fromDate:date];
  
    return [components week];
  }
  </code></pre>
  
  <p>Since this will only happen once a week it seems stupid to have a thread that will refresh my label once every second or so, but I want the label value to change at the exact second the week number change.</p>
  
  <p>I also want to update a label with the current time, that will actually be once a second, or once a minute depending on settings. Should that just be a thread that runs once a second?</p>