DragDownToDismissModal.swift

    var initialTouchPoint = CGPoint(x: 0, y: 0)
 
    override func awakeFromNib() {
        super.awakeFromNib()
        self.modalPresentationStyle = UIModalPresentationStyle.overFullScreen
//        self.modalTransitionStyle = .crossDissolve
    }
    
    func setPanGesture() {
        let panGesture = UIPanGestureRecognizer(target: self, action: #selector(panGestureDismiss(_:)))
        self.view.addGestureRecognizer(panGesture)
    }
    
    @objc func panGestureDismiss(_ sender: UIPanGestureRecognizer) {
        
        let touchPoint = sender.location(in: self.view.window)
        
        if sender.state == .began {
            initialTouchPoint = touchPoint
        } else if sender.state == .changed {
            if touchPoint.y - initialTouchPoint.y > 0 {
                self.view.frame = CGRect(x: 0, y: touchPoint.y - initialTouchPoint.y, width: self.view.frame.width, height: self.view.frame.height)
            }
        } else if sender.state == .ended || sender.state == .cancelled {
            if touchPoint.y - initialTouchPoint.y > 200 {
                self.dismiss(animated: true, completion: nil)
            } else {
                UIView.animate(withDuration: 0.3) {
                    self.view.frame = CGRect(x: 0, y: 0, width: self.view.frame.width, height: self.view.frame.height)
                }
            }
        }
    }