Localization

An app is localized when various UI elements and code provide information in various languages.

There are two approaches that can be used. Storyboard localization for elements set-up on the storyboard which tend to be static. Labels for example. The other approach is more dynamic using NSLocalizedString.

Storyboard Localization

The first step is select the project in the side bar. The blue, top icon. Next, select the project itself in the Project-Target list. In the Info section find the Localizations section and click on the plus icon and select the language(s) to be added, one by one.

Select add icon

You can selecte which storyboard to localize.

Choose storyboards

Notice that the storyboard selected have additional items in the Project Navigator

Additional storyboard files

Inside the localized file there are a series of comment-code lines for each UI element to be localized. The

/* Class = "UILabel"; text = "A New Heading"; ObjectID = "hva-ie-Tgq"; */
"hva-ie-Tgq.text" = "A New Heading";

The text inside quotes on the ledt side is the string ID. On the right side, inside the quotes is the text that can be changed to the language selected. The text in the original language is shown in quote in the first, comment line. After you determine the correct translation replace the text on the right hand side, second line. A couple of web resources for the translation include:

Here ""A New Heading" becomes "Une nouvelle rubrique". You might do the reverse translation to test the answer or ask a native speaker.

/* Class = "UILabel"; text = "A New Heading"; ObjectID = "hva-ie-Tgq"; */
"hva-ie-Tgq.text" = "Une nouvelle rubrique";

If you add another UI element, such as a label you can take the Object ID from the Identity Inspector.

Object ID in the Identity Inspector

Add two new lines and edit the Object ID in the comment line.

/* Class = "UILabel"; text = "A New Heading"; ObjectID = "hva-ie-Tgq"; */
"hva-ie-Tgq.text" = "Une nouvelle rubrique";

/* Class = "UILabel"; text = "Another Heading"; ObjectID = "j2l-3E-g9O"; */
"j2l-3E-g9O.text" = "Une autre rubrique";

Alternately go back to the Project-Target list and delete the language and re-add it. This will delete all the previous work so adding items is probably the easier method.

Using NSLocalizationString

Any UI element to be localized needs to have an outlet so that it can be reference unless it is generated in code. Now instead of defining the .text for this element use NSLocalizationString.

//  mainLabel.text = "Unpaired t test"
    mainLabel.text = NSLocalizedString("UnpairedTTest", comment: "The main heading")

The first string is a key that is replaced by the text in the language specified. Make this change for all the text fields in the app. This could be across any number of files. The terminal program genstrings is used to create the localized files. Open the terminal app and change directory to the folder containing the .swift files for the app. Enter the genstrings command followed by *swift.

cd xxxx

MyDirectory$ ls
AppDelegate.swift		ObjCBits.m
Assets.xcassets			ViewController.swift
Base.lproj			fr.lproj
Info.plist			nl.lproj
ObjCBits.h			tValue-Bridging-Header.h

MyDirectory$ genstrings *swift

MyDirectory$ ls
AppDelegate.swift		ObjCBits.m
Assets.xcassets			ViewController.swift
Base.lproj			fr.lproj
Info.plist			nl.lproj
Localizable.strings		tValue-Bridging-Header.h
ObjCBits.h

Note the new file: Localizable.strings. Add this file to the project. Select this file in the Project Navigator (left column) and select the File Inspector in the right hand column and click on Localize...

local5

Choose the English or Base language

local8

You can now select from the languages that were added to the Project previously from Project > Info > Localizations

Choose the languages

We now have localized strings for the base language and any additional languages, such as French.

local7

Looking at this file we see information for the localized string.

/* The main heading */
"UnpairedTTest" = "UnpairedTTest";

The string on the right can be replaced with the French translation "Test t non apparié" to give these lines in this localization file.

/* The main heading */
"UnpairedTTest" = "Test t non apparié";

Currency Localization

Although we could use the above techniques to change the currency there is another way. Use a number formatter. Here money is the value as a Double

let currencyFormatter = NumberFormatter()
currencyFormatter.numberStyle = .currency
        
money.text = currencyFormatter.string(from: NSNumber(value: money))

Testing the Localization

On the device or simulator go to the Settings app and go to General > Language & Region > iPhone Language and select the language to be tested. Click Done > Change to Language selected. After the device/simulator resets it will display the chosen language.

Localized currency can be tested by changing the Region in the Settings > General > Language & Region.

Index

Comments, Corrections, Suggestions: David Bourne (david@boomer.org)
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