I’ve created a small gem, Bruno, to convert a Localizable.strings (iOS) file to a strings XML file (Android) and vice-versa.

To install it:

$ gem install bruno

A Localizable.strings file in an iOS project looks like this:

"APP_NAME" = "Test App";
"INFO_TITLE" = "Information";
"INFO_SUBTITLE" = "More information";

And with a single command:

$ bruno convert --in Localizable.strings --out strings.xml

You will get this file:

<?xml version="1.0" encoding="UTF-8"?>
  <string name="APP_NAME">Test App</string>;
  <string name="TITLE_ACTIVITY_MAIN">;Test</string>;
  <string name="INFO_TITLE">;Information</string>;
  <string name="INFO_SUBTITLE">;More information</string>;

You can use a strings XML file from Android to convert it to iOS too:

$ bruno convert --in strings.xml --out Localizable.strings

You can find the Git repository here: https://github.com/josem/bruno with further instructions.