title: dequeue reusable cell always crashes
body: <p>in this code i add the programatic VC:</p>
  
  <pre><code>@IBAction func addPerson(_ sender: UIBarButtonItem) {
          let controller = CNContactPickerViewController()
          controller.delegate = self
          navigationController?.present(controller, animated: true, completion: nil)
      }
  </code></pre>
  
  <p>here i use to go on another VC when i click on a contact (to show info into cells and then i want to make a checkbox for phones/emails to show back in my first VC)</p>
  
  <pre><code>func contactPicker(_ picker: CNContactPickerViewController, didSelect contact: CNContact) {
          let vc = EditContactViewController()
          self.navigationController?.pushViewController(vc, animated: true)
  </code></pre>
  
  <p>i created a class for the next cell and i set up identifier as cell in storyboard
  when i do this in tableView cellForRowAtIndexPath</p>
  
  <pre><code>let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as? ConfigCell
  
  return cell!
  </code></pre>
  
  <p>this gives me:</p>
  
  <pre><code>fatal error: unexpectedly found nil while unwrapping an Optional value
  </code></pre>
  
  <p>i also tried withIdentifier,forIndexPath and it says:</p>
  
  <blockquote>
    <p>2016-11-12 01:35:28.626 iEvents3[2637:47714] *** Terminating app due
    to uncaught exception 'NSInternalInconsistencyException', reason:
    'unable to dequeue a cell with identifier cell - must register a nib
    or a class for the identifier or connect a prototype cell in a
    storyboard'</p>
  </blockquote>
  
  <p>i deleted reuse identifier and put it back again , cleaned the application, restart, everything.</p>
  
  <p>Thank You for your time!</p>