func setTabBarVisible(visible: Bool, animated: Bool) {

    //* This cannot be called before viewDidLayoutSubviews(), because the frame is not set before this time

    // bail if the current state matches the desired state
    if (tabBarIsVisible() == visible) { return }

    // get a frame calculation ready
    let frame = self.tabBarController?.tabBar.frame
    let height = frame?.size.height
    let offsetY = (visible ? -height! : height)

    // zero duration means no animation
    let duration: TimeInterval = (animated ? 0.3 : 0.0)

    //  animate the tabBar
    if frame != nil {
        UIView.animate(withDuration: duration) {
            self.tabBarController?.tabBar.frame = frame!.offsetBy(dx: 0, dy: offsetY!)
            return
        }
    }
}

func tabBarIsVisible() -> Bool {
    return (self.tabBarController?.tabBar.frame.origin.y)! < self.view.frame.maxY
}

// Call the function from tap gesture recognizer added to your view (or button)

@IBAction func tapped(_ sender: Any?) {
    setTabBarVisible(visible: !tabBarIsVisible(), animated: true)
}