ios 11 UITabBar UITabBarItem positioning issue

Question

I have built my app using new Xcode 9 beta for ios 11. I have found an issue with UITabBar where items are spread through the UITabBar and title is right aligned to the image. I have tried changing the code to get it to work but still not successful.

ios 10+

ios 11

I could change the position of title using tabBarItem.titlePositionAdjustment But that is not my requirement as it should automatically come bellow the image itself. I tried setting tabbar.itemPositioning to UITabBarItemPositioningCentered and also tried changing itemSpacing and width, but still did not work. Can someone help me understand why this happens and how to fix this? I want it to like ios 10+ version and images are taken from the left most corner of an iPad.

Solution 1

I am maintaining a large iPad app written mostly in Objective-C that has survived several iOS releases. I ran into the situation where I needed the pre-iOS 11 tab bar appearance (with the icons above the titles instead of next to them) for a couple tab bars. My solution was to create a subclass of UITabBar that overrides the traitCollection method so that it always returns a horizontally-compact trait collection. This causes iOS 11 to display the titles below the icons for all of the tab bar buttons.

In order to use this, set the custom class of the tab bars in the storyboard to this new subclass and change any outlets in the code that point to the tab bars to be of this new type (don't forget to import the header file below).

The .h file is pretty much empty in this case:

//
//  MyTabBar.h
//

#import <UIKit/UIKit.h>

@interface MyTabBar : UITabBar

@end

Here is the .m file with the implementation of the traitCollection method:

//
//  MyTabBar.m
//

#import "MyTabBar.h"

@implementation MyTabBar

// In iOS 11, UITabBarItem's have the title to the right of the icon in horizontally regular environments
// (i.e. the iPad).  In order to keep the title below the icon, it was necessary to subclass UITabBar and override
// traitCollection to make it horizontally compact.

- (UITraitCollection *)traitCollection {
    return [UITraitCollection traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassCompact];
}

@end

Solution 2

Based on John C's answer, here is the Swift 3 version that can be used programmatically without need for Storyboard or subclassing:

extension UITabBar {
    // Workaround for iOS 11's new UITabBar behavior where on iPad, the UITabBar inside
    // the Master view controller shows the UITabBarItem icon next to the text
    override open var traitCollection: UITraitCollection {
        if UIDevice.current.userInterfaceIdiom == .pad {
            return UITraitCollection(horizontalSizeClass: .compact)
        }
        return super.traitCollection
    }
}

Solution 3

To avoid messing up any other traits is it not better to combine with the superclasses:

- (UITraitCollection *)traitCollection
{
  UITraitCollection *curr = [super traitCollection];
  UITraitCollection *compact = [UITraitCollection  traitCollectionWithHorizontalSizeClass:UIUserInterfaceSizeClassCompact];

  return [UITraitCollection traitCollectionWithTraitsFromCollections:@[curr, compact]];
}

Solution 4

Swift 4 version with a subclass that avoids extension/category naming collision:

class TabBar: UITabBar {
  override var traitCollection: UITraitCollection {
    guard UIDevice.current.userInterfaceIdiom == .pad else {
      return super.traitCollection
    }

    return UITraitCollection(horizontalSizeClass: .compact)
  }
}

If you use Interface Builder and storyboards, you can select the tab bar view in your UITabBarController scene and change its class to TabBar in the Identity Inspector:

Solution 5

NOTE: This fix above seems to work quite nicely. Not sure how it will work in the future, but for now it's working quite well.

---

According to this WWDC talk, this is the new behavior for:

• iPhone in landscape
• iPad all the time

And if I'm reading correctly, this behavior cannot be changed:

We've got this brand new appearance for the tab bar, both in landscape and on iPad, where we show the icon and the text side by side. And in particular on iPhones the icon is smaller and the tab bar is smaller to give a bit more room vertically.

View more solutions

Comments

[massimobio]

I don't use storyboard/IB but I was able to get the exact same effect by subclassing UITabBarController instead of UITabBar and overriding the same traitCollection method.

[Daniele Ceglia]

Not only! It also works with storyboard/IB that use subclasses of UITabBarController with this fix...

[massimobio]

Actually scratch that. Subclassing UITabBarController is not recommended and in fact the navigation bar broke with iOS 11 GM when doing this.

[massimobio]

Any idea on how to programmatically use the UITabBar subclass in a stock UITabBarController?

[nolanw]

This is not recommended, though I'm not surprised to hear that it works at the moment. If UITabBar also overrides traitCollection, and/or if there's another extension (or Objective-C category) on UITabBar somewhere that implements it, then the result is undefined. You're better off subclassing (annoying as that is). See stackoverflow.com/questions/5267034/category-conflicts for more info.

[nolanw]

This is indeed better!

[nolanw]

@massimobio make a storyboard and instantiate your UITabBarController in code. (Seriously.)

[Niko Zarzani]

Unfortunately doing that breaks the navigation bar appearance (UIBarButtonItems and the nav bar title): forums.developer.apple.com/thread/86013

[Bharat Raichur]

Awesome..this works for me. When I just had the Compact size class set for trait collection, it fixed my tab bar items, but had broken my navigation bar buttons. Thank you!!

[Dan Rosenstark]

@nolanw Is there a way to use a subclass if you're merely using a UITabBarController? Note: this answer does work in that case, too.

[nolanw]

@DanRosenstark yep: use a storyboard. I have a storyboard in a project that has a plain UITabBarController whose only customization is setting its tab bar's class, and I load it in code. It's a pain in the butt, but it's safer than swizzling and much safer than hopping there's no category conflicts.

[Eugene Brusov]

@NikoZarzani It breaks the navigation bar appearance only if you subclass UITabBarController. In case you subclass UITabBar the navigation bar appearance left as it is.

[Eugene Brusov]

@nolanw You can also use separate xib file with tab bar controller as a root view in that xib layout. Then load tab bar controller with Bundle.main.loadNibNamed("MyTabBarController", owner: nil, options: [])?.first

[Eugene Brusov]

@BharatRaichur Subclass UITabBar not UITabBarController then override - (UITraitCollection *)traitCollection{...}. That won't brake your nav bar.

[Eugene Brusov]

This solution brakes Nav bar icons :(

[zaitsman]

Sadly, with iOS 13 this started producing this warning Class MyClass overrides the -traitCollection getter, which is not supported. If you're trying to override traits, you must use the appropriate API.

[Seoras]

Yes iOS 13 was giving me the same errors but if you use the solution below by @andy-c instead, most of those error messages disappear. That solution still spits out "[TraitCollection] Class CustomiPadUITabBar overrides the -traitCollection getter, which is not supported. If you're trying to override traits, you must use the appropriate API." Whatever the "appropriate API" is?

[Seoras]

iOS 13 was spitting out a large amount of debugs in the console about traits which this solution fixed. One error is still being report though "[TraitCollection] Class CustomiPadUITabBar overrides the -traitCollection getter, which is not supported. If you're trying to override traits, you must use the appropriate API.". Any ideas how to get rid of that one? Is there an "appropriate API" ?