Does MFMailComposeViewController come only in English!?
I am toying around with the idea of using MFMailComposeViewController to handle sending email from my app but I need it to conform to the language environments of devices set to languages other than english. Is it possible to set MFMailComposeViewController to other languages? Even if I set my device's language to, say, japanese, the MFMailComposeViewController's To:, From:, Subject:, portions remain in english. How does one change the language of MFMailComposeViewController?
MFMailComposeViewController will display in the language the application is translated into rather than the language the user has selected; this keeps the text within the application consistent. Add a language project for the language you are targeting and the composer view will adopt that language.
The Done button on the keyboard, the Delete button that shows when a UITableViewCell is swiped and other built-in views behave similarly.
来源：https://stackoverflow.com/questions/1321281/mfmailcomposeviewcontroller-in-other-languages