title: UIDeviceOrientationDidChange only works with iPhone 7
body: <p>I am trying to detect the orientation change in a certain ViewController. I use the notification and a custom function. With iPhone 7 (running iOS 10.2) every time the notification changes the rotated function is being called. But while using iPhone 6 (running 9.3) or iPhone 6s (running 10.0) the function is being called only <strong>once</strong>, when the screen loads, but not when I turn around the phone.</p>
  
  <p>Code: </p>
  
  <pre><code>func rotated() {
      if UIDevice.current.orientation.isLandscape {
          print("Landscape")
      } else {
          print("Portrait")
      }
  }
  
  override func viewDidLoad() {
      super.viewDidLoad()        
      UIDevice.current.beginGeneratingDeviceOrientationNotifications()
      NotificationCenter.default.addObserver(self, selector: #selector(ViewController.rotated), name: NSNotification.Name.UIDeviceOrientationDidChange, object: nil)
  }
  </code></pre>