title: Swift NSFetchedResultsController not sectioning based on sectionNameKeyPath
body: <pre><code>lazy var fetchedResultsController: NSFetchedResultsController&lt;StoryTemplatePack&gt; =
      {
          let managedObjectContext = (UIApplication.shared.delegate as! AppDelegate).managedObjectContext
  
          var frc: NSFetchedResultsController&lt;StoryTemplatePack&gt; = NSFetchedResultsController(fetchRequest: self.createFetchRequest(), managedObjectContext: managedObjectContext, sectionNameKeyPath: "sectionnum", cacheName: nil)
          frc.delegate = self
  
          return frc
  }()
  
  // FetchedResultsController: Create Request
  func createFetchRequest() -&gt; NSFetchRequest&lt;StoryTemplatePack&gt; {
      let fetchRequest = NSFetchRequest&lt;StoryTemplatePack&gt;(entityName: "StoryTemplatePack")
  
      fetchRequest.predicate = NSPredicate.init(format: "productidentifier != nil")
  
      fetchRequest.sortDescriptors = [
          NSSortDescriptor(key: "isfeatured", ascending: false),
          NSSortDescriptor(key: "ispurchased", ascending: true),
          NSSortDescriptor(key: "name", ascending: true)
      ]
  
  
      return fetchRequest
  }
  </code></pre>
  
  <p>The results should be sectioned according to the <code>sectionnum</code> property on StoryTemplatePack (which is a transient property calculated in code). </p>
  
  <p>When I loop over the results of the NSFetchedResultsController it shows the correct section numbers and story pack names. There should be 3 sections, but the FRC is reporting only 1 section. The dumped results also show that I'm sorting the results correctly so that the section values are monotonically increasing. </p>
  
  <pre><code>---- dumping frc, num sections: 1
      section 0 pack Incredible Journeys
      section 0 pack Out for a Date
      section 0 pack Party Time
      section 1 pack Holiday Craziness
      section 1 pack In the Office
      section 1 pack On the Internets
      section 1 pack On the Job
      section 1 pack School Daze
      section 1 pack Social Networking
      section 1 pack TV Troubles
      section 1 pack Technology Takes Over
      section 2 pack Christmas Shenanigans
  ---- done dumping
  </code></pre>
  
  <p><code>self.fetchedResultsController.sections!.count</code> is returning 1 when it should return 3.</p>
  
  <p>What am I doing wrong or missing?</p>