Ship a file with your app bundle (could be JSON, whatever you want) with all of the strings you'd want to be dynamic. Then on each app launch, check if it exist

Ship a file with your app bundle (could be JSON, whatever you want) with all of the strings you'd want to be dynamic. Then on each app launch, check if it exists in the Documents directory, and if not, copy it to the Documents directory. Place the same file somewhere web-accessible (an s3 bucket, for example) at a stable URL you can hard-code into your app. On each app launch, attempt to download this file and replace the existing one on disk with it. You could set a reasonable minimum time threshold before checking again (such as once per 24 hours), but this probably won't be an issue. After you've got that set up, change every hard-coded string in your app to read from this file you've downloaded. This works like localization, where each string has a key to identify it regardless of language.