how can I manage controllers in Container View with using tab bar - ios

Question

On my storyboard I have main ViewController, not TabBarViewController, which consist of TabBar on the bottom, view on the top and ContainerView on the middle. ContainerView have a NavigationController. I also have 4 ViewControllers, one of them - RootViewController of NavigationController. I wish to show one of ViewControllers when I selecting TabBarItem, and in future I will add slide menu, which also will show selected ViewController.
I have next code, which only shows initial ViewController inside ContainerView, and when I selecting TabBarItems, new ViewControllers don't showing and I see only first View Controller. What goes wrong?
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)
}
}
Storyboard screenshot:

Answer 1

You can try to use this extesion to add/remove any of the 4 to containerView
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()
}
}
// use it like this
let vc = self.storyboard?.instantiateViewController(withIdentifier: "first")
self.add(vc, frame: self.containerView.frame)
to remove
vc.remove()