Extension on UITabBarController for hiding/showing the tab bar.

UITabBarController+ToggleTabBar.swift

extension UITabBarController {

    /**
     Show or hide the tab bar.

     - Parameter hidden: `true` if the bar should be hidden.
     - Parameter animated: `true` if the action should be animated.
     - Parameter transitionCoordinator: An optional `UIViewControllerTransitionCoordinator` to perform the animation
        along side with. For example during a push on a `UINavigationController`.
     */
    func setTabBar(
        hidden: Bool,
        animated: Bool = true,
        along transitionCoordinator: UIViewControllerTransitionCoordinator? = nil
    ) {
        guard isTabBarHidden != hidden else { return }

        let offsetY = hidden ? tabBar.frame.height : -tabBar.frame.height
        let endFrame = tabBar.frame.offsetBy(dx: 0, dy: offsetY)
        let vc: UIViewController? = viewControllers?[selectedIndex]
        var newInsets: UIEdgeInsets? = vc?.additionalSafeAreaInsets
        let originalInsets = newInsets
        newInsets?.bottom -= offsetY

        /// Helper method for updating child view controller's safe area insets.
        func set(childViewController cvc: UIViewController?, additionalSafeArea: UIEdgeInsets) {
            cvc?.additionalSafeAreaInsets = additionalSafeArea
            cvc?.view.setNeedsLayout()
        }

        // Update safe area insets for the current view controller before the animation takes place when hiding the bar.
        if hidden, let insets = newInsets { set(childViewController: vc, additionalSafeArea: insets) }

        guard animated else {
            tabBar.frame = endFrame
            return
        }

        // Perform animation with coordinato if one is given. Update safe area insets _after_ the animation is complete,
        // if we're showing the tab bar.
        weak var tabBarRef = self.tabBar
        if let tc = transitionCoordinator {
            tc.animateAlongsideTransition(in: self.view, animation: { _ in tabBarRef?.frame = endFrame }) { context in
                if !hidden, let insets = context.isCancelled ? originalInsets : newInsets {
                    set(childViewController: vc, additionalSafeArea: insets)
                }
            }
        } else {
            UIView.animate(withDuration: 0.3, animations: { tabBarRef?.frame = endFrame }) { didFinish in
                if !hidden, didFinish, let insets = newInsets {
                    set(childViewController: vc, additionalSafeArea: insets)
                }
            }
        }
    }

    /// `true` if the tab bar is currently hidden.
    var isTabBarHidden: Bool {
        return !tabBar.frame.intersects(view.frame)
    }

}

I found this leaves a blank space if the view controller in your tab bar is a UIHostingViewController.

Heres the fix:

extension UITabBarController {
	/// Extends the size of the `UITabBarController` view frame, pushing the tab bar controller off screen.
	/// - Parameters:
	///   - hidden: Hide or Show the `UITabBar`
	///   - animated: Animate the change
	func setTabBarHidden(_ hidden: Bool, animated: Bool) {
		guard let vc = selectedViewController else { return }
		guard tabBarHidden != hidden else { return }
		
		let frame = self.tabBar.frame
		let height = frame.size.height
		let offsetY = hidden ? height : -height

		UIViewPropertyAnimator(duration: animated ? 0.3 : 0, curve: .easeOut) {
			self.tabBar.frame = self.tabBar.frame.offsetBy(dx: 0, dy: offsetY)
			self.selectedViewController?.view.frame = CGRect(
				x: 0,
				y: 0,
				width: vc.view.frame.width,
				height: vc.view.frame.height + offsetY
			)
			
			self.view.setNeedsDisplay()
			self.view.layoutIfNeeded()
		}
		.startAnimation()
	}
	
	/// Is the tab bar currently off the screen.
	private var tabBarHidden: Bool {
		tabBar.frame.origin.y >= UIScreen.main.bounds.height
	}
}