iOS 8中自定义呈现的视图控制器的在线状态栏(双高)状态栏如何进行布局？

为我工作的是为UIApplicationWillChangeStatusBarFrameNotification添加一个观察者,然后找到transitionContext.containerView()并更新框架.我注意到当查看调试时,当回到正常的状态栏高度时,transitionContext.containerView()框架没有被更新.

func willChangeStatusBarFrame(notification: Nsnotification)
{
    if let userInfo = notification.userInfo
    {
        if let value = userInfo[UIApplicationStatusBarFrameUserInfoKey] as? NSValue
        {
            let statusBarFrame = value.CGRectValue()
            let transitionView = UIApplication.sharedApplication().delegate!.window!!.subviews.last! as UIView
            var frame = transitionView.frame
            frame.origin.y = statusBarFrame.height-20
            frame.size.height = UIScreen.mainScreen().bounds.height-frame.origin.y
            UIView.animateWithDuration(0.35) {
                transitionView.frame = frame
            }
        }
    }
}