Drag down view controller to dismiss. Swift 5

UIViewController+DragToDismissGesture.swift

override func viewDidLoad() {
    super.viewDidLoad()
    let gestureRecognizer = UIPanGestureRecognizer(target: self,
                                                   action: #selector(panGestureRecognizerHandler(_:)))
    view.addGestureRecognizer(gestureRecognizer)
}

@IBAction func panGestureRecognizerHandler(_ sender: UIPanGestureRecognizer) {
    let touchPoint = sender.location(in: view?.window)
    var initialTouchPoint = CGPoint.zero

    switch sender.state {
    case .began:
        initialTouchPoint = touchPoint
    case .changed:
        if touchPoint.y > initialTouchPoint.y {
            view.frame.origin.y = touchPoint.y - initialTouchPoint.y
        }
    case .ended, .cancelled:
        if touchPoint.y - initialTouchPoint.y > 200 {
            dismiss(animated: true, completion: nil)
        } else {
            UIView.animate(withDuration: 0.2, animations: {
                self.view.frame = CGRect(x: 0,
                                         y: 0,
                                         width: self.view.frame.size.width,
                                         height: self.view.frame.size.height)
            })
        }
    case .failed, .possible:
        break
    }
}

/*
When viewcontroller is half or smaller from normal fixed size
*/
        //    @IBOutlet weak var pickerContentView: UIView!
        @IBAction func panGestureRecognizerHandler(_ sender: UIPanGestureRecognizer) {
        guard let rootView = view, let rootWindow = rootView.window else { return }
        let rootWindowHeight: CGFloat = rootWindow.frame.size.height

        let touchPoint = sender.location(in: view?.window)
        var initialTouchPoint = CGPoint.zero
        let blankViewHeight =  (rootWindowHeight - pickerContentView.frame.size.height)
        let dismissDragSize: CGFloat = 200.00

        switch sender.state {
        case .began:
            initialTouchPoint = touchPoint
        case .changed:
            // dynamic alpha
            if touchPoint.y > (initialTouchPoint.y + blankViewHeight)  { // change dim background (alpha)
                view.frame.origin.y = (touchPoint.y - blankViewHeight) - initialTouchPoint.y
            }

        case .ended, .cancelled:
            if touchPoint.y - initialTouchPoint.y > (dismissDragSize + blankViewHeight) {
                dismiss(animated: true, completion: nil)
            } else {
                UIView.animate(withDuration: 0.2, animations: {
                    self.view.frame = CGRect(x: 0,
                                             y: 0,
                                             width: self.view.frame.size.width,
                                             height: self.view.frame.size.height)
                })
                // alpha = 1
            }
        case .failed, .possible:
            break
        }
    }