Updated: December 2020
With a global app market, it only makes sense to develop apps that operate in native languages with cultural sensitivity. Apple has provided developers with a rich set of tools, features, and functionality to support well over a hundred different world languages.
At first, the problem seems simple – just replace the text with a language-specific version. Instead of defining the text that gets displayed as hard-coded strings within the software, the text for each language/region is defined in a separate strings file. A language-specific strings file within each app is selected (if the app supports language localization) by setting the language for the iPhone or iPad device in the device ‘Language & Region’ option under ‘General’ within ‘Settings’.
Even with all the support structure that is in place, providing a native language and an engaging cultural app experience is amazingly complex with a mind-numbing set of details to consider and resolve:
Singularity and plurality of things
Dates and calendars
Currency symbols and formatting
Numbers and formats
Alphabets and punctuation
Gender assignment to things
Sorting a list
And, that doesn’t even begin to consider the accuracy of translations and relevant context. Some of the complexity of getting localization and internationalization correct is humorously presented by Tom Scott in the following video.
Tips and Best Practices:
I am using the following design guidelines and practices to enable localization and globalization for apps. Many of these guidelines and practices are not my own, but a collection of best practices from the developer community.
Even if just a single language is used for the app, setting up the files for localization and internationalization code consolidates the text strings in a few files. This is so much easier than searching through all the code files to find a text string to edit.
Start with the localization and internationalization code and the configuration setup from the start. It is so much harder to retrofit an app design and the software code.
Use localized string dictionary files for handling singular and plural phrases. Various languages implement singular and plural differently in phrases.
Use flexible sizing of localized fields since the text length will vary between languages.
Localize the title of the app that displays under the icon.
Use NSDateFormatter when displaying dates. Use NSNumberFormatter when displaying numbers. Pass NSLocale currentLocale into NSDateFormatter and NSNumberFormatter.
Use a naming convention approach. With a large number of individual items in an app to be converted to various languages, it is crucial to develop at the start a naming convention that will be consistent throughout the software code. For example:
NSLocalizedString("aboutscreen.title.welcome", comment: "comment about context")
Configuring for Localization and Internationalization:
Project configuration to support localization and internationalization for the mobile device family (iPhone, iPad) and the Mac are slightly different. As such, each are separately described.
Commonality of Localization and Internationalization Resources:
Some of the localization and internationalization files can be shared as a common resource for Xcode projects involving both an iOS and a MacOS target: ‘Localizable.strings’, ‘InfoPlist.strings’, ‘Localizable.stringsdict’. To enable sharing, check the box next to each target under ‘Target Membership’ in the Xcode ‘Inspector Pane’ for each file.
Manually selecting a language on an iPhone or iPad (e.g., Settings app > General > Languages & Region) is not conducive to testing a localized app in development for two reasons:
Lots of manual steps to change the language.
The language change affects all localizable apps on the device including all text within File >’Settings’ confounding the ability to make subsequent changes.
Creating language schemes that can be selected as part of the Xcode runtime configuration is a more versatile app testing approach that works with either the device simulator or an actual iPhone/iPad device seamlessly. There are at least three ways to access the screen to create a localized scheme:
From an Xcode shortcut key: ⌘ ⇧ <
From an Xcode toolbar: click on the app target, then select ‘Edit Scheme …‘ from the dropdown menu
From the Xcode menu: select ‘Product > Scheme > Edit Scheme …‘
On the left side of the panel, select ‘Run‘ and select ‘Options‘ as shown.
Select ‘Duplicate Scheme‘ and rename the scheme (i.e., top left corner). It is good practice to include the language in the scheme name. Then, select the application language (e.g., French) and application region for each localization scheme (e.g., France). Then, this scheme will override the current values in NSUserDefaults during app execution from Xcode. Selecting this scheme from the scheme list will change the localization for the app for testing without changing any other app’s localization on the actual device.
To add localization and internationalization to an app takes extra effort and requires a healthy attention to detail. This post only touches on the first steps and doesn’t describe localizing date/time formats, plurals, number formats, currency formats, and getting language translations. And, that is why I identify with the following quote:
“Those who care enough to take the extra time to internationalize their app are very likely to be just as thoughtful when it comes to design and implementation.”
Internationalization and Localization Guide
Internationalization – Right to Left Support for Mobile Apps
Where the &$!#% is localizable.strings?!?
New Localization Workflows in Xcode 10
Keeping dates local
Plurals localization using Stringsdict in iOS