swift - UITabBarController.selectedIndex 崩溃

Question

我在“UITabBarController.selectedIndex”上发生崩溃。令人惊讶的是，选项卡栏在执行的任何时候都不会为零，并且在该特定行上仍然会出现错误。请指导我找到正确的解决方案。

        let obj = self.storyboard?.instantiateViewControllerWithIdentifier("OfferViewController") as! OfferViewController
        setFlagWhilePushingFromMenuViewController()

        obj.screenName = SCREEN.MOBILE_RECHARGE.rawValue
        rechargeManager.presentRechargeScreen = PRESENT_SCREEN.MOBILE.rawValue

        if let tab : UITabBarController = self.revealViewController().frontViewController as? UITabBarController{
            let index : Int =  tab.selectedIndex // CRASH POINT
            print("----->\(tab.selectedIndex)")

            tab.selectedIndex = 1
            let navig : UINavigationController = tab.viewControllers![index] as! UINavigationController

            navig.pushViewController(obj, animated: true)
            self.revealViewController().revealToggleAnimated(true)
        }
        else{
            print("do something else")
        }

Answer 1

要获取 tabar 的 selectedIndex，请应用以下代码，

var application: AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
var tabbarController = application.tabBarController as UITabBarController
var selectedIndex = tabBarController!.selectedIndex

你会得到这样的selectedIndex。它在这里工作。