title: Simple Fetch in Swift 3 Core Data
body: <p>I've been trying to implement a simple core data functionality within my app so that it shows a tutorial (a separate view controller with a scroll page) only the first time the app loads, and bypasses it every other time.
  I started with syntax from CoreData tutorials for Swift 2, but then had to tweak based on Swift 3's auto corrections and other tutorials that helped me overcome the errors i found along the way (such as SIGBRT). The current problem I'm having is a EXC_BAD_INSTRUCTION error, which I need help fixing.</p>
  
  <p>I've got a scrollViewController with the following code:</p>
  
  <pre><code>class ScrollViewController: UIViewController, NSFetchedResultsControllerDelegate {
  
  @IBOutlet var mainScrollView: UIScrollView!
  
  @IBOutlet weak var endTutorial: UIButton!
  
  var imageArray = [UIImage]()
  
  class Person: NSManagedObject {
      @NSManaged var tutorialstatus: String?
  }
  
  func seed() {
      let moc = DataController().managedObjectContext
      let entityDes = NSEntityDescription.entity(forEntityName: "Person", in: moc)
      let entity = Person(entity: entityDes!, insertInto: moc)
      entity.tutorialstatus="test value"
      do {
          try moc.save()
      } catch {
          fatalError("Failure to save context: \(error)")
      }
  }
  
  func fetch() {
      let moc = DataController().managedObjectContext
      let personFetch = NSFetchRequest&lt;Person&gt;(entityName: "Person")
  
  
      do {
          let fetchedPerson = try moc.fetch(personFetch)
          print(fetchedPerson.first!.tutorialstatus)
  
      } catch {
          fatalError("Failed to fetch person: \(error)")
      }
  }
  </code></pre>
  
  <p>At the <code>let fetchedPerson = try moc.fetch(personFetch)</code> line, when I try to compile, I see the error <strong>EXC_BAD_INSTRUCTION (code=EXC_1386_INVOP, subcode=0x0)</strong></p>
  
  <p>I am using Xcode 8, Beta 8.
  I have a swift file called 'CoreDataStuf.xcdatamodeld which has an entity named "Person" with an attribute called tutorialstatus, which is a string. I've also given that entity a class of Person. 
  I also have a DataController.swift file where i refer to the URL CoreDataStuf. </p>