Apple iPhone 6 Plus display languages
Solution 1:
Apple eventually added the Persian keyboard and language to the list of the iPhone keyboards and preferred languages back in 2017. Now all iPhones with iOS 11+ can add Persian keyboard and or language in their iPhone Settings > General > Keyboards or .. > Language & Region.
Prior to iOS 11, Persian users could install the Arabic keyboard and long-press ک - ج - ب - ز - ي keys to input the Persian letters گ - چ - پ - ژ - ی.