iOS 9 brings complete right-to-left support for Arabic, Hebrew, and other languages. Going beyond basic text, your app’s entire interface can now flip to provide a native right-to-left experience. Learn what behavior you get for free from UIKit, and hear details about adding right-to-left support in custom interfaces. Hear from experts about how to evaluate the readiness of your app for these languages. Understand best practices to avoid common pitfalls and to create a seamless bi-directional app.
WWDC 2015 > App Frameworks > New UIKit Support for International User Interfaces