Is it possible to have a program built for two countries and change the appearance and language of the program due to the SIM card code on the device?
Yes. You can check user's language for this.
Get the language key of localization:
let preferredLanguage = NSLocale.preferredLanguages.first
Also you can get country code.
Also you can do it using user's location, but I think it is a bad approach. Location requires a lof of battery.