如何使用标签栏在Container View中管理控制器

Question

在我的故事板上，我有主ViewController ，而不是TabBarViewController，它由底部的TabBar ，顶部的视图和中间的ContainerView 。 ContainerView有一个NavigationController 。 我也有4个ViewControllers ，其中之一- RootViewController的NavigationController 。 我希望在选择TabBarItem时显示其中一个ViewControllers ，将来我将添加幻灯片菜单，该菜单还将显示所选的ViewController。
我有下一个代码，该代码仅显示ContainerView内的初始ViewController，并且当我选择TabBarItems时，不显示新的ViewController，并且仅看到第一个View Controller。 怎么了？

class ViewController: UIViewController {

    @IBOutlet weak var container: UIView!
    @IBOutlet weak var first: UITabBarItem!
    @IBOutlet weak var second: UITabBarItem!
    @IBOutlet weak var third: UITabBarItem!
    @IBOutlet weak var fours: UITabBarItem!
    @IBOutlet weak var tabBar: UITabBar!

    var firstVC: FirstViewController?
    var secondVC: SecondViewController?
    var thirdVC: ThirdViewController?
    var foursVC: FoursViewController?

    var navi: UINavigationController?




    override func viewDidLoad() {
        super.viewDidLoad()
        tabBar.delegate = self
        initialSetup()
    }

    func initialSetup() {

        tabBar.selectedItem = tabBar.items?.first

        navi = self.storyboard?.instantiateViewController(withIdentifier: "containerNavi") as? UINavigationController

        firstVC = self.storyboard?.instantiateViewController(withIdentifier: "FirstViewController") as? FirstViewController
        secondVC = self.storyboard?.instantiateViewController(withIdentifier: "SecondViewController") as? SecondViewController
        thirdVC = self.storyboard?.instantiateViewController(withIdentifier: "ThirdViewController") as? ThirdViewController
        foursVC = self.storyboard?.instantiateViewController(withIdentifier: "FoursViewController") as? FoursViewController
    }

    func showVC(number: Int) {
        switch number {
        case 0:
            navi?.popToRootViewController(animated: true)
            print("0")
        case 1:
            if let second = secondVC {
                navi?.pushViewController(second, animated: true)
            }
            print("1")
        case 2:
            if let third = thirdVC {
                navi?.pushViewController(third, animated: true)
            }
            print("2")
        case 3:
            if let fours = foursVC {
                navi?.pushViewController(fours, animated: true)
            }
            print("3")
        default:
            return
        }
    }


}

extension ViewController: UITabBarDelegate {

    func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
        showVC(number: item.tag)
    }

}

故事板截图：

Answer 1

您可以尝试使用此功能将4种功能之一添加/删除到ContainerView中

extension UIViewController {
    func add(_ child: UIViewController, frame: CGRect? = nil) {
        addChildViewController(child)
        if let frame = frame {
            child.view.frame = frame
        }
        view.addSubview(child.view)
        child.didMove(toParentViewController: self)
    }
    func remove() {
        willMove(toParentViewController: nil)
        view.removeFromSuperview()
        removeFromParentViewController()

   }

}

//这样使用

let vc = self.storyboard?.instantiateViewController(withIdentifier: "first")

self.add(vc, frame: self.containerView.frame)

去除

vc.remove()