当我在 appdelegate swift 中设置 Tabbar 时，如何设置 viewcontroller 的根视图？

Question

我已经在 AppDelegate 中设置了 UITabBarController 并且我已经将根视图设置为标签栏对象。但是我需要在不丢失选项卡栏功能的情况下将根视图设置为另一个视图控制器。我怎样才能做到这一点？

  let vc1 = ConstituencyViewController()
    //vc1.view.backgroundColor = UIColor.orange
    vc1.tabBarItem.title = "Search"
    vc1.tabBarItem.image = UIImage(named: "Search")

    // Set up the second View Controller
    let vc2 = ConstDetailViewController()
    //vc2.view.backgroundColor = UIColor.purple
    vc2.tabBarItem.title = "User"
    vc2.tabBarItem.image = UIImage(named: "Street View")

    // Set up the Tab Bar Controller to have two tabs
    let tabBarController = UITabBarController()

    tabBarController.viewControllers = [vc1, vc2]

    // Make the Tab Bar Controller the root view controller
    window?.rootViewController = tabBarController
    window?.makeKeyAndVisible()

Answer 1

 let appDelegate = UIApplication.shared.delegate as! AppDelegate

    let vc1 = ConstDetailViewController()
            //vc1.view.backgroundColor = UIColor.orange
            vc1.tabBarItem.title = "Search"
            vc1.tabBarItem.image = UIImage(named: "Search")

    let vc2 = OptionsViewController()

    vc2.tabBarItem.title = "Search"
    vc2.tabBarItem.image = UIImage(named: "Street View")

            // Set up the second View Controller

            //vc2.view.backgroundColor = UIColor.purple

            // Set up the Tab Bar Controller to have two tabs
            let tabBarController = UITabBarController()

            tabBarController.viewControllers = [vc1,vc2]
    appDelegate.window?.rootViewController = tabBarController
    appDelegate.window?.makeKeyAndVisible()

当我在 appdelegate swift 中设置 Tabbar 时，如何设置 viewcontroller 的根视图？

How can I set rootview of a viewcontroller when I have set Tabbar in appdelegate swift?

uitabbarcontroller

ios

rootview

swift3