iOS Question This OC code how to change b4i

Private Sub Application_Start (Nav As NavigationController)
   NavControl = Nav
   Page1.Initialize("Page1")
   NavControl.ShowPage(Page1)
   Dim no As NativeObject = Me
   no.RunMethod("addListener", Null)
End Sub

#if OBJC
- (void)addListener {
   [[NSNotificationCenter defaultCenter] addObserver:self
     selector:@selector(_orientation_changed)
     name:UIDeviceOrientationDidChangeNotification object:nil];
}
#end if

Private Sub Orientation_Changed
   Log($"Current orientation: ${DeviceOrientation}"$)
End Sub

Private Sub DeviceOrientation As String
  Dim no As NativeObject
  Dim o As Int = no.Initialize("UIDevice").RunMethod("currentDevice", Null).RunMethod("orientation", Null).AsNumber
  Select o
  Case 0
  Return "Unknown"
  Case 1
  Return "Portrait"
  Case 2
  Return "PortraitUpsideDown"
  Case 3
  Return "LandscapeLeft"
  Case 4
  Return "LandscapeRight"
  Case 5
  Return "FaceUp"
  Case 6
  Return "FaceDown"
  End Select
  Return "Unknown"
End Sub

Dim no As NativeObject
    no.Initialize("NSNotificationCenter").RunMethod("defaultCenter", Null) _
     .RunMethod("addObserver:self selector:@selector(orientationChanged) name:UIDeviceOrientationDidChangeNotification    object:nil", _
       Null)