You can not change an signed iOS, MacOS or Android app, if the app is not yours. But if you have the source, the app is your, you have many options to save the resources strings, you can save in particular files for it. When we are talking about resources strings for translation, this will allow the store to make smallest packages of your app, because it will not delivery the unnecessary data to the user. For example, a French language will not be included in a user that use English language ... However, this languages files isn’t usually big, and I personally prefer to make a cross platform solution, languages in the source code. Other solution is storing it in a SQLite.