Internalization and Localization of iPhone and iPod Touch Applications

August 2009 by PLG

Precision Language & Graphics (PLG) provides assistance on how to localize your applications into any languages you choose so that your iPhone apps will find much wider markets.

According to Apple’s web site, the iPhone is currently sold in 80 countries and is expected to continue to surpass this. In the United States, iPhones are set in languages other than English such as Spanish. Localizing your applications can be a viable approach to promote your iPhone App to a wider non-English speaking audience in North America and the rest of the world.

Image-Left: A Spanish-speaking iPhone user is writing an e-mail in a localized e-mail application by using the iPhone's built-in Spanish language keyword capabilities. Click to view.




Options You Have to Writing Localized Applications

There are 2 approaches to writing the iPhone application so that it has multiple language interfaces.

You may program all the localized items in the core program. There are a few drawbacks to this approach:

1. You have to share the source code engine with the localization partner so that the lines can be localized properly

2. The final product will be multiple applications different only by languages.

The proper approach to writing localized applications is to use the tools provided by iPhone development kit:  Localization Folder and Localizable.strings.

Write Applications for Non-English Speaking iPhone Users

Localization Folder - In developing iPhone applications intended for both English and other language speaking users, the developer creates the so-called “Localization Folders”.  Each language has its own folder.  The naming of the folder must follow the convention specified in the application development protocol.  For example, if one works on a French version of an application, the folder’s name will be fr_FR.lproj, in which “fr” is the ISO two-digit language code for French and “FR” is the ISO two-digit country code for France.  All known languages have their own three-digit codes while some commonly used languages have two-digit codes. Therefore, if the launched application can not find the language and country in form of the two-digit codes, it will look for the ISO three-digit code.  For detailed information and codes, please visit the ISO webpage at http://www.iso.org/iso/iso_3166_code_lists and http://en.wikipedia.org/wiki/List_of_ISO_639-1_codes.

String Files – In a localized application, the translated text is placed in a file called “localizable.string”.  The file will be placed in the Localization Folder. This file has the following features:

1. Since each language has its own localization folder, fr_FR.lproj for French for example, the string file in this folder is named as “localizable.string”. No language needs to be identified in the file name.

2. This file is text file coded with UTF-16.

3. The Localization Folder may have other resource files that need to be localized. For example, some graphic files with embedded texts may need to be localized. Other examples may be national flags, country maps or other text and settings that the application will present accordingly to the targeted language.

Coding Samples
The code for the following application targets both English and French speaking users.  In a section of the user interface, number One, Two, Three, Four and Five will show. In the core code, these 5 numbers are called:

	 label1.text = NSLocalizedString(@"One", @"The number 1");
	 label2.text = NSLocalizedString(@"Two", @"The number 2");
	 label3.text = NSLocalizedString(@"Three", @"The number 3");
	 label4.text = NSLocalizedString(@"Four", @"The number 4");
	 label5.text = NSLocalizedString(@"Five", @"The number 5");

Next, in the “en_US.lproj” folder, there is a file called “localizable.string”.  The contents of the file are as follows:

	 /* The number 5 */
	 "Five" = "Five";
	 /* The number 4 */
	 "Four" = "Four";
	 /* The number 1 */
	 "One" = "One";
	 /* The number 3 */
	 "Three" = "Three";
	 /* The number 2 */
	 "Two" = "Two";

In the “fr_FR.lproj” folder, another file named “localizable.string” exists as well. The contents in this folder should be changed to:

	 /* The number 5 */
	 "Five" = "Cinq";
	 /* The number 4 */
	 "Four" = "Quatre";
	 /* The number 1 */
	 "One" = "Un";
	 /* The number 3 */
	 "Three" = "Trois";
	 /* The number 2 */
	 "Two" = "Deux";

Strings are localized in the format "key" = "value". The key and the value strings are in double quotes followed by a semi-colon.

Depending on the language setup in the iPhone configuration file settings, the application will call the English localizable.string file for English viewers and the French localizable.string file for French users. When a user changes their default language on their phone by going to Settings --> General --> International --> Language, the iPhone will change the language settings of the iPhone application if supported.

Translation Services We Provide

We highly recommend the application developers to implement the second approach by creating a localization folder and a string file for each language. 

We can assist by having the application developer send us the “localizable.string” file in text format.  Our best-in-class language professionals will translate the strings and place them back into the file.  

Other Aspects of Localization

Strictly speaking, the aforementioned text localization activity is often defined as internalization.  The word “localization” is reserved for correctly converting and displaying cultural information like units, dates, currencies and other information that must be “culturally correct” in a global marketing drive. Please contact a PLG localization professional for support on localizing the information.

Application Description – In the iPhone App store, the application is introduced to potential buyers by the Application Description.  We strongly recommend the description to be translated or at least an abstract in the target language to be provided. Since your iPhone app could be downloaded by any iPhone user in any country, we strongly recommend that the app behaves according to the user’s location in both language context and settings. This is the developer’s best ally to winning the heart of those non-English speaking iPhone users in other markets.

Source(s): apple.com/iphone

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