January 25, 2018

Hiding the UITabBar of a UITabBarController

For some reason, that is beyond my imagination, there is no public API for hiding the UITabBar of a UITabBarController on iOS. Sure there’s the .hidesBottomBarWhenPushed. But I never get that to work the way I expect it to. And furthermore, it does not help when I want to hide the bar after a push, or at any arbitrary point in time.

So I wrote up this little extension on UITabBarController that adds a method for toggling the tab bar’s visibility. It does a simple slide down-animation to get it out of the way. If you want you can pass a UIViewControllerTransitionCoordinator object to the method as well, to perform the animation together with a view controller transition.

It’s not super-well tested, but it works for me. There’s a gist if you have ideas for improvements or just want to ask questions.

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

        // 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

        // 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)