注销后未设置TabbarController badgeValue

Question

我第一次能够在tabbar Controller上设置badgeValue但是在注销后我无法设置tabbar badgeValue，它总是返回nil。

      let tabArray = self.navigationController?.tabBarController?.tabBar.items as NSArray!


        if(tabArray != nil)
        {
           let tabItem = tabArray.objectAtIndex(3) as! UITabBarItem
                tabItem.badgeValue = "100";
        }else
        {
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            let main_tabbar = storyboard.instantiateViewControllerWithIdentifier("tabbar") as! tabbar
            let tabArray = main_tabbar.tabBar.items as NSArray!


            if(tabArray != nil)
            {
         //...........Problem is Here ......
                let tabItem = tabArray.objectAtIndex(3) as! UITabBarItem
                tabItem.badgeValue = "100"; //Here is not Update but code working
            }else
            {
              print("Not gatting tabbar")
            }

        }

在故事板上我创建了TabbarController，并设置标识名称为“tabbar”，类名为tabbar。

这是我的代码在“退出”按钮上我显示第一页：

let storyboard = UIStoryboard(name: "Main", bundle: nil)
       let initialViewController = storyboard.instantiateViewControllerWithIdentifier("FirstNavigation")
         UIApplication.sharedApplication().delegate?.window??.rootViewController = initialViewController
         UIApplication.sharedApplication().delegate?.window??.makeKeyAndVisible()