swift – 在tvOS 10 GM上打开UIAlertController时焦点消失了

override var preferredFocusedView: UIView? {
    return self.collectionView
}

使用tvOS 9一切正常：警报控制器正常打开,我可以选择其中一个显示的UIAlertActions.

在tvOS 10 Golden Master上,打开警报控制器并滚动到另一个动作后,焦点从屏幕上消失,我无法滚动到其他操作或点击Siri遥控器的菜单按钮.该应用程序仍然卡在警报控制器中,当我尝试滚动到其他操作但屏幕上没有任何操作时,我可以听到滚动声音.我必须强制退出应用程序并重新打开它.

这是应用程序的代码.我尝试将preferredFocusableView设置为alertController.preferredFocusedView,或者删除集合视图的焦点方法但没有结果.

var alertController : UIAlertController?

func showAlert() {

    alertController = UIAlertController(title:"Example title",message: "Example description",preferredStyle: .Alert)

    let action1 = UIAlertAction(title: "Option 1",style: .Default) { (action : UIAlertAction) -> Void in
        //call to another method
    }

    // action2,action3,action4...

    let action5 = UIAlertAction(title: "Option 5",style: .Default) { (action : UIAlertAction) -> Void in
        //call to another method
    }

    let actionDismiss = UIAlertAction(title: "Dismiss",style: .Destructive) { (action : UIAlertAction) -> Void in
        self.alertController!.dismissViewControllerAnimated(true,completion: nil)
    }

    alertController!.addAction(action1)
    alertController!.addAction(action2)
    alertController!.addAction(action3)
    alertController!.addAction(action4)
    alertController!.addAction(action5)
    alertController!.addAction(actionDismiss)

    alertController!.preferredAction = action1

    self.presentViewController(alertController!,animated: true,completion: nil)
}

override var preferredFocusedView: UIView? {
    if self.alertController != nil {
        return self.alertController!.preferredFocusedView
    } else {
        return self.collectionView
    }
}