iOS 11 & iPhone X: UINavigationBar's toolbar spacing incorrect when embedded in UITabBarController

Question

I am experiencing an annoying problem testing the newest iOS 11 on the iPhone X simulator.

I have an UITabBarController and inside each tab there is a UINavigationController, each UINavigationBar has defined also a bottom toolBar (setToolbarHidden:), and by default they show up at the bottom, just over the tabBar.

It has been working fine so far and seems to work fine also in the upcomming iPhone 8 and 8 Plus models, but on the iPhone X there is a gap between the toolBar and the tabBar. My guess is that the toolBar doesn't realize that is displayed inside a tabBar and then leaves the accommodating space at the bottom.

I guess the only way to fix it would be using a custom toolbar and display/animate it myself instead of using the defaults UINavigationBar, but I would like to hear other options :)

• This is how it looks on iPhone 8.
• And here is the problem on iPhone X.

Answer 1

I filed this as radr://problem/34421298, which was closed as a duplicate of radr://problem/34462371. However, in the latest beta of Xcode 9.2 (9C32c) with iOS 11.2, this seems to be fixed. Here's an example of my app running in the simulator of each device, with no changes in between.

This isn't really a solution to your problem, other than that some patience may solve it without needing to resort to UI trickery. My assumption is that iOS 11.2 will be out before the end of the year, since it's needed to support HomePod.

Answer 2

If you don't consider rotations you can try to manipulate the layer of the toolbar as a very hacky yet fast workaround.

class FixNavigationController: UINavigationController
{
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        updateTollbarPosition()
    }

    func updateTollbarPosition() {
        guard let tabbarFrame = tabBarController?.tabBar.frame else {
            return
        }
        let gapHeight = tabbarFrame.origin.y-toolbar.frame.origin.y-toolbar.frame.size.height

        var
        frame = toolbar.layer.frame
        frame.origin.y += gapHeight

        toolbar.layer.frame = frame
    }    
}

Unfortunately, rotation animation doesn't look good when it comes to this approach. In this case, adding the custom toolbar instead of the standard one will be a better solution.

Answer 3

I have found only one workaround: add toolbar directly to the view controller

Answer 4

iOS 11.1 and iPhone X are released and this bug/feature isn't fixed yet. So I implemented this workaround. This code works in iOS 9.0+.

Just set this class in your storyboard as navigation controller's class. It will use custom toolbar in iPhone X with correct layout constraints, and falls back to native one in other devices. The custom toolbar is added to navigation controller's view instead of your view controller, to make transitions smoother.

• Important Note: You have to call updateItems(animated:) manually after setting toolbarItems of your view controller to update interface. If you set toolbarItems property of navigation controller, you can ignore this step.

It simulates all native toolbar behavior (including changing toolbar height in portrait/landscape modes), except push/pop animations.

import UIKit

class FixNavigationController: UINavigationController {

    private weak var alterToolbarHeightConstraint: NSLayoutConstraint?

    private var _alterToolbar: UIToolbar?

    private func initAlretToolbar() {
        _alterToolbar = UIToolbar()
        _alterToolbar!.isTranslucent = true
        _alterToolbar!.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(_alterToolbar!)
        if view.traitCollection.verticalSizeClass == .compact {
            alterToolbarHeightConstraint = _alterToolbar!.heightAnchor.constraint(equalToConstant: 32.0)
        } else {
            alterToolbarHeightConstraint = _alterToolbar!.heightAnchor.constraint(equalToConstant: 44.0)
        }
        let bottomAnchor: NSLayoutConstraint
        if #available(iOS 11.0, *) {
            bottomAnchor = _alterToolbar!.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor)
        } else {
            bottomAnchor = _alterToolbar!.bottomAnchor.constraint(equalTo: bottomLayoutGuide.topAnchor)
        }
        NSLayoutConstraint.activate([
            _alterToolbar!.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            _alterToolbar!.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            bottomAnchor,
            alterToolbarHeightConstraint!
            ])
        self.view.updateFocusIfNeeded()
        self.view.layoutIfNeeded()
    }

    private var alterToolbarInSuper: UIToolbar? {
        var superNavigationController = self.navigationController as? FixNavigationController
        while superNavigationController != nil {
            if superNavigationController?._alterToolbar != nil {
                return superNavigationController?._alterToolbar
            }
            superNavigationController = superNavigationController?.navigationController as? FixNavigationController
        }
        return nil
    }

    private var alterToolbar: UIToolbar! {
        get {
            if let t = alterToolbarInSuper {
                return t
            }
            if _alterToolbar == nil {
                initAlretToolbar()
            }
            return _alterToolbar
        }
    }

    // This is the logic to determine should use custom toolbar or fallback to native one
    private var shouldUseAlterToolbar: Bool {
        // return true if height is iPhone X's one
        return UIScreen.main.nativeBounds.height == 2436
    }

    /// Manually call it after setting toolbar items in child view controllers
    func updateItems(animated: Bool = false) {
        if shouldUseAlterToolbar {
            (_alterToolbar ?? alterToolbarInSuper)?.setItems(viewControllers.last?.toolbarItems ?? toolbarItems, animated: animated)
        }
    }

    override var isToolbarHidden: Bool {
        get {
            if shouldUseAlterToolbar {
                return _alterToolbar == nil && alterToolbarInSuper == nil
            } else {
                return super.isToolbarHidden
            }
        }
        set {
            if shouldUseAlterToolbar {
                if newValue {
                    super.isToolbarHidden = newValue
                    _alterToolbar?.removeFromSuperview()
                    _alterToolbar = nil
                    self.view.updateFocusIfNeeded()
                    self.view.layoutIfNeeded()
                    // TODO: Animation when push/pop
                    alterToolbarHeightConstraint = nil
                    var superNavigationController = self.navigationController as? FixNavigationController
                    while let superNC = superNavigationController {
                        if superNC._alterToolbar != nil {
                            superNC._alterToolbar?.removeFromSuperview()
                            superNC._alterToolbar = nil
                            superNC.view.updateFocusIfNeeded()
                            superNC.view.layoutIfNeeded()
                        }
                        superNavigationController = superNC.navigationController as? FixNavigationController
                    }
                } else {
                    alterToolbar.setItems(viewControllers.last?.toolbarItems ?? toolbarItems, animated: false)
                }
            } else {
                super.isToolbarHidden = newValue
            }
        }
    }

    override func setToolbarItems(_ toolbarItems: [UIBarButtonItem]?, animated: Bool) {
        super.setToolbarItems(toolbarItems, animated: animated)
        updateItems(animated: animated)
    }

    override var toolbarItems: [UIBarButtonItem]? {
        get {
            return super.toolbarItems
        }
        set {
            super.toolbarItems = newValue
            updateItems()
        }
    }

    override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        guard let _alterToolbar = _alterToolbar else {
            return
        }
        self.alterToolbarHeightConstraint?.isActive = false
        let height: CGFloat = (view.traitCollection.verticalSizeClass == .compact) ? 32.0 : 44.0
        let alterToolbarHeightConstraint = _alterToolbar.heightAnchor.constraint(equalToConstant: height)
        alterToolbarHeightConstraint.isActive = true
        self.alterToolbarHeightConstraint = alterToolbarHeightConstraint
    }
}

Answer 5

Apple still has not yet fixed this bug in iOS 11.2. Derived from Mousavian's solution, here is a simpler approach that I took.

I took this approach because I have just one UITableViewController where this bug happens. So in my case, I just added the following code listed below to my ViewController (which is UITableViewController) where this bug happens.

Advantages are:

• This fix just takes over in case of an iPhone X. No side effects to expect on other devices
• Works with any transition
• Works regardless of other parent/child controllers having Toolbars or not
• Simple

And here is the code:

1.Add startFixIPhoneXToolbarBug to your viewWillAppear like this:

override func viewWillAppear(_ animated: Bool)
{
    super.viewWillAppear(animated)

    startFixIPhoneXToolbarBug()
}

2.Add endFixIPhoneXToolbarBug to your viewWillDisappear like this:

override func viewWillDisappear(_ animated: Bool)
{
    super.viewWillDisappear(animated)

    endFixIPhoneXToolbarBug()
}

3.Implement start/endFixIPhoneXToolbarBug in your viewController like this:

private var alterToolbarHeightConstraint: NSLayoutConstraint? = nil
private var alterToolbar: UIToolbar? = nil

func startFixIPhoneXToolbarBug()
{
    // Check if we are running on an iPhone X
    if UIScreen.main.nativeBounds.height != 2436
    {
        return  // No
    }
    // See if we have a Toolbar
    if let tb:UIToolbar = self.navigationController?.toolbar
    {
        // See if we already added our own
        if alterToolbar == nil
        {
            // Should always be the case
            if let tbView = tb.superview
            {
                // Create a new Toolbar and apply correct constraints
                alterToolbar = UIToolbar()
                alterToolbar!.isTranslucent = true
                alterToolbar!.translatesAutoresizingMaskIntoConstraints = false
                tb.isHidden = true
                tbView.addSubview(alterToolbar!)
                if tbView.traitCollection.verticalSizeClass == .compact
                {
                    alterToolbarHeightConstraint = alterToolbar!.heightAnchor.constraint(equalToConstant: 32.0)
                }
                else
                {
                    alterToolbarHeightConstraint = alterToolbar!.heightAnchor.constraint(equalToConstant: 44.0)
                }
                let bottomAnchor: NSLayoutConstraint
                if #available(iOS 11.0, *)
                {
                    bottomAnchor = alterToolbar!.bottomAnchor.constraint(equalTo: tbView.safeAreaLayoutGuide.bottomAnchor)
                }
                else
                {
                    bottomAnchor = alterToolbar!.bottomAnchor.constraint(equalTo: bottomLayoutGuide.topAnchor)
                }
                NSLayoutConstraint.activate([
                    alterToolbar!.leadingAnchor.constraint(equalTo: tbView.leadingAnchor),
                    alterToolbar!.trailingAnchor.constraint(equalTo: tbView.trailingAnchor),
                    bottomAnchor,
                    alterToolbarHeightConstraint!
                    ])
                tbView.updateFocusIfNeeded()
                tbView.layoutIfNeeded()
            }
        }
        // Add the original items to the new toolbox
        alterToolbar!.setItems(tb.items, animated: false)
    }
}

func endFixIPhoneXToolbarBug()
{
    if alterToolbar != nil
    {
        alterToolbar!.removeFromSuperview()
        alterToolbar = nil
        alterToolbarHeightConstraint = nil

        if let tb:UIToolbar = self.navigationController?.toolbar
        {
            tb.isHidden = false
        }
    }
}