This lowercase function takes a locale argument https://developer.apple.com/documentation/foundation/nsstring/1417298-lowercased https://developer.apple.com/doc

This lowercase function takes a locale argument https://developer.apple.com/documentation/foundation/nsstring/1417298-lowercased https://developer.apple.com/documentation/foundation/nsstrin... It looks like an old NSString method that's available in both Obj-C and Swift. The casefold function is even older than that. https://developer.apple.com/documentation/foundation/nsstring/1413779-folding https://developer.apple.com/documentation/foundation/nsstrin... Its documentation specifically includes a discussion of the Turkish İ/I issue.