Random Wok 1.0 is currently not localized: the only language it supports is English. Before I release the 1.1 version I am going to add translations for the languages that Aperture supports: French, German, and Japanese. This requires extra files in the plugin's bundle that provide the language information.

To prepare, I replace all the messages and strings that are generated by the program and are human-readable with macros that retrieve the localized version. Code like this:

is replaced by code like this:

I use the NSLocalizedStringWithDefaultValue macro because it allows me to provide a key (exporting-images in this case) that is not the same as the string Exporting Images.... It also supports use of a specific bundle. I need that because Random Wok is a plugin and otherwise Aperture's main bundle would be used.

Once I have replaced all the strings in my code with macros, I use the terminal to run the genstrings utility on all the source files in my project:

I get this entry in the text file Localizable.strings created by genstrings for the exporting-images string above:

To provide for other languages the Localizable.strings file is duplicated and the string on the right replaced by the translation. When the plugin is run, the correct language files in the bundle are accessed and the key used in the code (exporting-images) matched with the entry in the file. Since the file is encoded UTF-16, the right hand string can contain ASCII and any unicode characters.

There are two other sources of strings that I need to worry about for localization in my plugin. First, the nib file contains all the strings used in the interface and it is currently English-only. To fix that I will need a new nib file for each language and will probably have to adjust the placement of some interface elements due to the size of the new strings. Second, I have an image that is displayed when there is no thumbnail available that says "No Image". That will have to be replaced with a new image for each language.

Apple provides a tool for helping with the translation of nibs called nibtool. Nibtool used with the -L option extracts all the strings from a nib file and sends them to stdout. The Random Wok nib file generates entries like these:

As before, a translation replaces the right hand string. Nibtool is used again to replace the strings in copies of the nib file with the translated versions.

The other parts of this series can be found via the Cocoa page.

Tags: Aperture, Plug-ins, Localization, Cocoa, Random Wok