Apple's update brings full support for a mirrored user interface that automatically flips interface elements and animations to conform with the expectations of readers of right-to-left languages. For example, someone who uses Arabic as their system language will be able to swipe from right to left in order to unlock an iPhone or iPad, rather than left to right. That same consideration applies to the entire operating system: icons on a device's home screen are added from the right to left and sliders reach their maximum value at the left-hand edge of the screen, rather than the right.
"This is what the UI would look like if it was designed by a native Hebrew or Arabic speaker," Toby Paterson, an engineering manager at Apple, said during the Platforms State of the Union session at the company's Worldwide Developers Conference on Monday.
Sara Radi, an Apple software engineer and native Arabic speaker, demonstrated the Mail app for iOS 9 running on an iPhone with Arabic as its primary language. Instead of placing a list of messages on the left-hand side of the screen and the message contents on the right side of the screen when the phone was in landscape mode, all of the user interface elements were flipped. The demonstration drew cheers and applause from the assembled developers attending the session.
Radi said that third-party developers who use Apple's system frameworks to build their apps will get similar functionality largely "for free" in their own apps when they add language support for a right-to-left language thanks to system user interface elements that automatically mirror themselves. Those app makers with custom functionality will be able to re-work apps for right-to-left localization using a new API that reports which way the interface is flowing.
It's a marked improvement over the current state of iOS, which supports Hebrew and Arabic, but currently features an interface with system controls that match the English layout, which can be disorienting.