What should you know about a navigation history stack in iOS 14


Prior to iOS 14, If you are deep down in a navigation stack, the only way to go back is to smash your back button until you reach the root level. This is no longer a case in iOS 14.

With iOS 14, if you're deep down in a navigation stack and want to head back to any level quickly, you can long-press the back button to bring up the history stack.

Example of a history stack of Settings
Example of a history stack of Settings

Why should we care about this? #

At first glance, this looks like a nice feature and nothing we need to do to adopt this. We get this behavior automatically when building our app against iOS 14 SDK.

The problem is, it is quite a trend nowadays that designers would design an app without a back button title. The following are some example apps without a back button title.

Apps that have no back button title. Pinterest (left), Tasty (Middle), and Google news (Right)
Apps that have no back button title. Pinterest (left), Tasty (Middle), and Google news (Right)

Without a back button title, history stack will look like this (I assume you hide back button title with this method).

History stack without back button title
History stack without back button title

Where does history stack pick up the title? #

To solve this problem, we need to know which string is used as titles in a history stack. From my testing, a history stack getting the title from a navigation back button title, not the navigation title.

Scenarios #

Let's test this out in different scenarios. In the following examples, I set up an AViewController where the right navigation item is pushing another AViewController to itself.

Only title #

If we set only title, this title will also use as a back button title and also use in a history stack.

class AViewController: UIViewController {
override func viewDidLoad() {
title = "Title A"
}
}
Back button title is getting from the title
Back button title is getting from the title

Long title #

If your title is long enough, the back button title will be shortened to just "Back" for saving space, but this won't affect a title in a history stack.

Back button title show as
Back button title show as "Back" for a long title
Title show in history stack still use the full title
Title show in history stack still use the full title

Customize back button title #

As mentioned before, a back button title string will be used in a history stack. So, the text in backButtonTitle will be used as a title in a history stack if set.

class AViewController: UIViewController {
override func viewDidLoad() {
title = "Title A"
navigationItem.backButtonTitle = "Custom back title A"
}
}
Custom back button title
Custom back button title
Value in backButtonTitle will be used as history title
Value in backButtonTitle will be used as history title

No title #

Since history stack depends on the back button title, set empty title won't affect a history stack. You can design an app with or without a title since this won't affect a history stack.

class AViewController: UIViewController {
override func viewDidLoad() {
title = ""
navigationItem.backButtonTitle = "Custom back title A"
}
}
Empty title
Empty title

No back button title #

This is the most interesting scenario of all since an empty back button title is quite popular among designers.

class AViewController: UIViewController {
override func viewDidLoad() {
title = "Title A"
navigationItem.backButtonTitle = ""
}
}
Empty back title
Empty back title
Empty back title will result in empty history title
Empty back title will result in empty history title

As you can see, this is the most harmful design for iOS 14. Does this mean we have to tell our designers to put back a button title from now on? Luckily, the answer is no. We can work around this problem.

Solution #

We know that a back button title must be there for history stack to pick up a title. So, we have to set backButtonTitle a value you want to show in history and then try to hide it in UI.

Change offset (not work) #

The first idea that comes up is setting negative x offset like what we sometimes do with a CSS styling. You can hide a back button title with this method, but you will suffer from transition animation. You will see a title slide beyond the back button indicator.

UIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffset(horizontal:-500, vertical: 0), for: .compact)
UIBarButtonItem.appearance().setBackButtonTitlePositionAdjustment(UIOffset(horizontal:-500, vertical: 0), for: .default)
Try to hide back button title by set negative offset
Try to hide back button title by set negative offset

Transparent color #

This solution is quite straight forward. We set a back button title color to transparent. This method uses some knowledge from UINavigationBar changes in iOS13, you might want to check it out.

let appearance = UINavigationBarAppearance()
appearance.configureWithDefaultBackground()

appearance.backButtonAppearance.normal.titleTextAttributes = [.foregroundColor: UIColor.clear]

UINavigationBar.appearance().standardAppearance = appearance
UINavigationBar.appearance().compactAppearance = appearance
Transition animation look perfect with clear color
Transition animation look perfect with clear color
History stack show as normal
History stack show as normal

Conclusion #

This looks like a subtle change, but it requires some extra work on both the design and implementation phases. You can continue to design an app without a back button title, but make sure you provide a name for each view for a history stack.


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