Xcode - how to use localized string from attribute inspector

in the attribute inspector i have a placeholder (a.k.a a hint) for a textfield. The hint is called USERNAME. I'd like to localize this. I have already added the necessary strings into a localizable.strings file. My question is i would rather reference this string from the inspector itself. I wish i could do something like localstrings(@"username") right inside the placeholder field itself. I wish i could localize the placeholder string directly from interface builder is what i'm asking for. I've attached an image showing what i'd like to accomplish.