private func showWarningView() {

        DispatchQueue.main.async { [weak self] in

            guard let self = self else { return }

            var newConstant: CGFloat!

            if self.warningViewTopConstraint.constant == 0.0 {
                newConstant = 100.0
            } else {
                newConstant = 0.0
            }

            self.warningViewTopConstraint.constant = newConstant

            UIView.animate(withDuration: 0.25, delay: 0.0, options: .curveEaseIn, animations: { [weak self] in
                guard let self = self else { return }
                self.view.layoutIfNeeded()
            }, completion: nil)

        }

    }