在iOS中旋转时,inputAccessoryView的UIToolbar变黑

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view,typically from a nib.

    let keyBoardToolBar = UIToolbar(frame: CGRectMake(0,self.view.frame.size.width,44))
    keyBoardToolBar.barStyle = .Default

    let flexSpaceKeyboardBarButtonItem = UIBarButtonItem(barButtonSystemItem: .FlexibleSpace,target: nil,action: nil)

    let doneKeyboardBarButtonItem = UIBarButtonItem(title: "Done",style: .Done,target: self,action: nil)

    let wordKeyboardBarButtonItem = UIBarButtonItem(title: "Button 1",style: .Plain,action: nil)

    var barItems: [UIBarButtonItem] = []
    barItems.append(wordKeyboardBarButtonItem)
    barItems.append(flexSpaceKeyboardBarButtonItem)
    barItems.append(doneKeyboardBarButtonItem)

    keyBoardToolBar.setItems(barItems,animated: true)

    self.myTV.inputAccessoryView = keyBoardToolBar
}

当我转动设备时,UIToolBar变黑了(点击再次查看此GIF)

那么无论如何要修复它？谢谢！

顺便说一句：在模拟器中,我看不到UIToolBar变黑了.