Q:

Addding UIView between tabBar and Navigation view in UITabBarController

I am working on a project that uses a UITabBarController for displaying all the different UIViewControllers but now I need to add a mini player just in between the tabBar and the navigation view (ViewControllers will have to resize too).  
Is there anyway I can achieve that by reusing the existing class? 
EDIT
I have tried 2 methods:
1- Adding it into the view.  Gets Added but above of the VCs
let aView = UIView()
view.addSubview(aView)
aView.backgroundColor = .white
aView.anchor(top: nil, leading: view.leadingAnchor, bottom: tabBar.topAnchor, trailing: view.trailingAnchor, size: .init(width: 0, height: 100))

2- Adding it into the tabBar.  It might sound silly but I thought It would work. 
let viewOverTabBar = UIView(frame: CGRect(x: 0, y: 0, width: 30, height: 30))
viewOverTabBar.backgroundColor = UIColor.black
tabBar.addSubview(viewOverTabBar)

A:

You can try this way : 
class MyTabBarController: UITabBarController {

     override func viewDidLoad() {
         super.viewDidLoad()

        // Do any additional setup after loading the view. 
    }

     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         self.createSmallPlayer()
    }

    func createSmallPlayer() {

        let viewOverTabBar = UIView(frame: CGRect(x: 0, y: self.tabBar.frame.origin.y-40, width: self.tabBar.frame.size.width, height: 30))
        viewOverTabBar.backgroundColor = UIColor.brown

        //viewOverTabBar.layer.cornerRadius = viewOverTabBar.frame.size.height/2
        viewOverTabBar.layer.masksToBounds = false
        viewOverTabBar.layer.shadowColor = UIColor.black.withAlphaComponent(0.5).cgColor
         viewOverTabBar.layer.shadowRadius = 5.0
        viewOverTabBar.layer.shadowOffset = CGSize(width: 0.0, height: -5.0)
        viewOverTabBar.layer.shadowOpacity = 0.5

        //tabBar.addSubview(viewOverTabBar)
        view.addSubview(viewOverTabBar)
    }
}

And make sure that your all other view controller(which will navigate within tabbar) adjust frame accordingly. 

Either you have to manage bottom view of all view controller by 30 pixels up and keep 30 pixels space blank at bottom, so no any content hide behind your player view. 
Or you have you add :

Container view UIView same as added player view. 
In that you have to add view controller's view with navigation controller as subview(Refer this : Adding a view controller as a subview in another view controller). 