title: Use of unresolved identifier NSCalendarUnitDay
body: <p>I just updated Xcode to its 6.3 version.</p>
  
  <p>Except all the fixes I have to make regarding <code>as</code> (mainly), I have some warnings that just appeared (which is weird as it states it is since iOS 8.0).</p>
  
  <p>My code</p>
  
  <pre><code>NSCalendar.currentCalendar().compareDate(self, toDate: date, toUnitGranularity: .DayCalendarUnit) == .OrderedAscending
  </code></pre>
  
  <p>is now shows a warning</p>
  
  <pre><code>'DayCalendarUnit' was deprecated in iOS version 8.0: Use NSCalendarUnitDay instead
  </code></pre>
  
  <p>Fine, then I'll change <code>.DayCalendarUnit</code> by <code>NSCalendarUnitDay</code></p>
  
  <p>Now I get an error saying:</p>
  
  <pre><code>Use of unresolved identifier 'NSCalendarUnitDay'
  </code></pre>
  
  <p>I'm confuse, can someone explain me what's wrong and how to fix it?</p>