I have a Storyboard in Xcode 5.1 with a base Localization of English, and a second Localization in French.
When I\'m using the Xcode Storyboard editor the strings a
Just click on you storyboard file and you can devellope it to show your Localization storyboard. In Your case if you use the localization "base" option, you must see 3 storyboard file (one for "base localization", one for english and one for french). Sorry for my english but i hope that help you.
I believe that Xcode is not prepared to show localized storyboards in Interface Builder when using string files. However, it allows for you to convert formats quite easily. Select your storyboard file and in the utilities panel, select the language you want to preview:
Change the "Localizable Strings" to "Interface Build Cocoa Touch Storyboard":
You should now be able to select the French storyboard file and preview it within IB.
Once you are done, you can convert the file back to "Localizable Strings" reversing this procedure, or using your source code version control system. Then you can update the base file with any necessary adjustments, and verify it is to your liking using this method again.
Xcode 6 now includes a feature to do this.
From What's New in Xcode - New Features in Xcode 6:
Preview in Interface Builder. While designing in Interface Builder, the preview assistant can show how the interface appears in other languages. You can see how your interface responds to longer or shorter languages.
Hurrah!