You can do it, if you want too... just click on your icon file (consider Icon.png) now simply click on the ‘+’ in that ‘Localization’ pane on the right.
Add languanges that you want to provide support. Consider you have English And Spanish language support, add those two languages. It will create ‘en.lproj’ and ‘es.lproj’.
Now just see those directory, you can see both directories have their own copy of Icon.png. So just replace that image and make sure new file has same name as the replaced one.
Now Run it. And check by changing language in Setting>International>Language
Basic thing is based on language it will check if localization is available for that particular resource, if it exists it will be used.