I was able to get around the problem by simply calling invalidateIntrinsicContentSize on the UITabBar in viewDidLayoutSubviews.

-(void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];
    [self.tabBar invalidateIntrinsicContentSize];
}

Note: The bottom of the tab bar will need to be contained to the bottom of the main view, rather than the safe area, and the tab bar should have no height constraint.

Answer provided by VoidLess fixes TabBar problems only partially. It fixes layout problems within the tabbar, but if you use viewcontroller that hides the tabbar, the tabbar is rendered incorrectly during animations (to reproduce it is best 2 have 2 segues - one modal and one push. If you alternate the segues, you can see the tabbar being rendered out of place). The code bellow fixes both problems. Good job apple.

class SafeAreaFixTabBar: UITabBar {

var oldSafeAreaInsets = UIEdgeInsets.zero

@available(iOS 11.0, *)
override func safeAreaInsetsDidChange() {
    super.safeAreaInsetsDidChange()

    if oldSafeAreaInsets != safeAreaInsets {
        oldSafeAreaInsets = safeAreaInsets

        invalidateIntrinsicContentSize()
        superview?.setNeedsLayout()
        superview?.layoutSubviews()
    }
}

override func sizeThatFits(_ size: CGSize) -> CGSize {
    var size = super.sizeThatFits(size)
    if #available(iOS 11.0, *) {
        let bottomInset = safeAreaInsets.bottom
        if bottomInset > 0 && size.height < 50 && (size.height + bottomInset < 90) {
            size.height += bottomInset
        }
    }
    return size
}

override var frame: CGRect {
    get {
        return super.frame
    }
    set {
        var tmp = newValue
        if let superview = superview, tmp.maxY != 
        superview.frame.height {
            tmp.origin.y = superview.frame.height - tmp.height
        }

        super.frame = tmp
        }
    }
}

Objective-C code:

@implementation VSTabBarFix {
    UIEdgeInsets oldSafeAreaInsets;
}


- (void)awakeFromNib {
    [super awakeFromNib];

    oldSafeAreaInsets = UIEdgeInsetsZero;
}


- (void)safeAreaInsetsDidChange {
    [super safeAreaInsetsDidChange];

    if (!UIEdgeInsetsEqualToEdgeInsets(oldSafeAreaInsets, self.safeAreaInsets)) {
        [self invalidateIntrinsicContentSize];

        if (self.superview) {
            [self.superview setNeedsLayout];
            [self.superview layoutSubviews];
        }
    }
}

- (CGSize)sizeThatFits:(CGSize)size {
    size = [super sizeThatFits:size];

    if (@available(iOS 11.0, *)) {
        float bottomInset = self.safeAreaInsets.bottom;
        if (bottomInset > 0 && size.height < 50 && (size.height + bottomInset < 90)) {
            size.height += bottomInset;
        }
    }

    return size;
}


- (void)setFrame:(CGRect)frame {
    if (self.superview) {
        if (frame.origin.y + frame.size.height != self.superview.frame.size.height) {
            frame.origin.y = self.superview.frame.size.height - frame.size.height;
        }
    }
    [super setFrame:frame];
}


@end

There is a trick by which we can solve the problem.

Just put your UITabBar inside a UIView.

This is really working for me.

Or you can follow this Link for more details.

override UITabBar sizeThatFits(_) for safeArea

extension UITabBar {
    static let height: CGFloat = 49.0

    override open func sizeThatFits(_ size: CGSize) -> CGSize {
        guard let window = UIApplication.shared.keyWindow else {
            return super.sizeThatFits(size)
        }
        var sizeThatFits = super.sizeThatFits(size)
        if #available(iOS 11.0, *) {
            sizeThatFits.height = UITabBar.height + window.safeAreaInsets.bottom
        } else {
            sizeThatFits.height = UITabBar.height
        }
        return sizeThatFits
    }
}

I added this to viewWillAppear of my custom UITabBarController, because none of the provided answers worked for me:

tabBar.invalidateIntrinsicContentSize()
tabBar.superview?.setNeedsLayout()
tabBar.superview?.layoutSubviews()

Aha! It's actually magic!

I finally figured this out after hours of cursing Apple.

UIKit actually does handle this for you, and it appears that the shifted tab bar items are due to incorrect setup (and probably an actual UIKit bug). There is no need for subclassing or a background view.

UITabBar will "just work" if it is constrained to the superview's bottom, NOT to the bottom safe area.

It even works in Interface builder.

Correct Setup

1. In interface builder, viewing as iPhone X, drag a UITabBar out to where it snaps to the bottom safe area inset. When you drop it, it should look correct (fill the space all the way to the bottom edge).
2. You can then do an "Add Missing Constraints" and IB will add the correct constraints and your tab bar will magically work on all iPhones! (Note that the bottom constraint looks like it has a constant value equal to the height of the iPhone X unsafe area, but the constant is actually 0)

Sometimes it still doesn't work

What's really dumb is that you can actaully see the bug in IB as well, even if you add the exact constraints that IB adds in the steps above!

1. Drag out a UITabBar and don't snap it to the bottom safe area inset
2. Add leading, trailing and bottom constraints all to superview (not safe area) Weirdly, this will fix itself if you do a "Reverse First And Second Item" in the constraint inspector for the bottom constraint. ¯_(ツ)_/¯

Fixed by using subclassed UITabBar to apply safeAreaInsets:

class SafeAreaFixTabBar: UITabBar {

    var oldSafeAreaInsets = UIEdgeInsets.zero

    @available(iOS 11.0, *)
    override func safeAreaInsetsDidChange() {
        super.safeAreaInsetsDidChange()

        if oldSafeAreaInsets != safeAreaInsets {
            oldSafeAreaInsets = safeAreaInsets

            invalidateIntrinsicContentSize()
            superview?.setNeedsLayout()
            superview?.layoutSubviews()
        }
    }

    override func sizeThatFits(_ size: CGSize) -> CGSize {
        var size = super.sizeThatFits(size)
        if #available(iOS 11.0, *) {
            let bottomInset = safeAreaInsets.bottom
            if bottomInset > 0 && size.height < 50 {
                size.height += bottomInset
            }
        }
        return size
    }
}

My case was that I had set a custom UITabBar height in my UITabBarController, like this:

  override func viewWillLayoutSubviews() {            
        var tabFrame = tabBar.frame
        tabFrame.size.height = 60
        tabFrame.origin.y = self.view.frame.size.height - 60
        tabBar.frame = tabFrame
    }

Removing this code was the solution for the TabBar to display correctly on iPhone X.

The simplest solution I found was to simply add a 0.2 pt space between the bottom of the tab bar and the bottom of the safeAreaLayoutGuide.bottomAnchor like so.

tabBar.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -0.2)

I encountered this today with a a UITabBar manually added to the view controller in the storyboard, when aligning to the bottom of the safe area with a constant of 0 I would get the issue but changing it to 1 would fix the problem. Having the UITabBar up 1 pixel more than normal was acceptable for my application.

I have scratched my head over this problem. It seems to be associated with how the tabBar is initialized and added to view hierarchy. I also tried above solutions like calling invalidateIntrinsicContentSize, setting the frame, and also bottomInsets inside a UITabBar subclass. They seem to work however temporarily and they break of some other scenario or regress the tab bar by causing some ambiguous layout issue. When I was debugging the issue I tried assigning the height constraints to the UITabBar and centerYAnchor, however neither fixed the problem. I realized in view debugger that the tabBar height was correct before and after the problem reproduced, which led me to think that the problem was in the subviews. I used the below code to successfully fix this problem without regressing any other scenario.

- (void) viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIViewControllerTransitionCoordinator>)coordinator
{
    [super viewWillTransitionToSize:size withTransitionCoordinator:coordinator];
    if (DEVICE_IS_IPHONEX())
    {
        [coordinator animateAlongsideTransition:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
            for (UIView *view in self.tabBar.subviews)
            {
                if ([NSStringFromClass(view.class) containsString:@"UITabBarButton"])
                {
                    if (@available (iOS 11, *))
                    {
                        [view.bottomAnchor constraintEqualToAnchor:view.superview.safeAreaLayoutGuide.bottomAnchor].active = YES;
                    }
                }
            }
        } completion:^(id<UIViewControllerTransitionCoordinatorContext>  _Nonnull context) {
            [self.tabBar layoutSubviews];
        }];
    }
}

Assumptions: I am doing this only for iPhone X, since it doesn't seem to reproduce on any other device at the moment. Is based on the assumption that Apple doesn't change the name of the UITabBarButton class in future iOS releases. We're doing this on UITabBarButton only when means if apple adds more internal subviews in to UITabBar we might need to modify the code to adjust for that.

Please lemme know if this works, will be open to suggestions and improvements!

It should be simple to create a swift equivalent for this.

I had the similar problem, at first it was rendered correctly but after setting up badgeValue on one of the tabBarItem it broke the layout. What it worked for me without subclassing UITabBar was this, on my already created UITabBarController subclass.

-(void)viewDidLayoutSubviews {
    [super viewDidLayoutSubviews];
    NSLayoutYAxisAnchor *tabBarBottomAnchor = self.tabBar.bottomAnchor;
    NSLayoutYAxisAnchor *tabBarSuperviewBottomAnchor = self.tabBar.superview.bottomAnchor;
    [tabBarBottomAnchor constraintEqualToAnchor:tabBarSuperviewBottomAnchor].active = YES;
    [self.view layoutIfNeeded];
}

I used tabBar superview to make sure that the constraints/anchors are on the same view hierarchy and avoid crashes.

Based on my understanding, since this seems to be a UIKit bug, we just need to rewrite/re-set the tab bar constraints so the auto layout engine can layout the tab bar again correctly.

If you have any height constraint for the Tab Bar try removing it .

Faced the same problem and removing this solved the issue.

I created new UITabBarController in my storyboard and pushed all view controllers to this new UITabBarConttoller. So, all work well in iPhone X simulator.

try to change splash screen with @3x size is (3726 × 6624)

For me, remove [self.tabBar setBackgroundImage:] work, maybe it's UIKit bug

For me this fixed all the issues:

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        let currentHeight = tabBar.frame.height
        tabBar.frame = CGRect(x: 0, y: view.frame.size.height - currentHeight, width: view.frame.size.width, height: currentHeight)
    }

I was using a UITabBarController in the storyboard and at first it was working alright for me, but after upgrading to newer Xcode version it started giving me issues related to the height of the tabBar.

For me, the fix was to delete the existing UITabBarController from storyboard and re-create by dragging it from the interface builder objects library.

For those who write whole UITabBarController programmatically, you can use UITabBarItem.appearance().titlePositionAdjustment to adjust the title position

So in this case that you want add a gap between Icon and Title use it in viewDidLoad:

    override func viewDidLoad() {
        super.viewDidLoad()

        // Specify amount to offset a position, positive for right or down, negative for left or up
        let verticalUIOffset = UIOffset(horizontal: 0, vertical: hasTopNotch() ? 5 : 0)

        UITabBarItem.appearance().titlePositionAdjustment = verticalUIOffset
    }

detecting if device has Notch screen:

  func hasTopNotch() -> Bool {
      if #available(iOS 11.0, tvOS 11.0, *) {
        return UIApplication.shared.delegate?.window??.safeAreaInsets.top ?? 0 > 20
      }
      return false
  }

For me the solution was to select the Tab Bar in the view hierarchy, then go to: Editor -> Resolve Auto Layout Issues, and under "Selected Views" (not "All views in view") choose "Add missing constraints".

I think this is a bug UIKit from iPhoneX. because it works:

if (@available(iOS 11.0, *)) {
    if ([UIApplication sharedApplication].keyWindow.safeAreaInsets.top > 0.0) {
       self.tabBarBottomLayoutConstraint.constant = 1.0;
    }
} 

I believe you might be laying out the tab bar against the bottom safe layout guide. This is probably not what you want since the tab bar does seems to do its own calculations to position the tab bar items safely on top of the home line in the iPhone X. Setup your bottom constraint against the superview bottom. You should see that it lays out correctly on iPhone X as well as other iPhones.

I ran into this bug on my launch screen storyboard, which can't be customised via subclassing. After some analysis I managed to figure out the cause - I was using a UITabBar directly. Switching to a UITabBarController, which encapsulates a UITabBar, solved the issue.

Note - it is possible that this will be fixed by iOS 11.1, so may not effect real iPhone X apps (since it is likely that the iPhone X will be released running iOS 11.1).