xCodeGridTranslator it's a simple mac app that able to edit ios app's localization files in a grid Editor View, just select a xCode project folder, and app will find and display all variables.
All variabiles are grouped by file name, and are displayed in a grid, to edit a variable just click on text and modify it, the original file will be immediatly write!
It's easy to find missing translations, in fact, they will be colored with red background.
