Apple has officially unveiled the iPhone Duo, its first foldable device, and detailed how third-party apps will adapt to the larger display. The company introduced three compatibility modes for apps targeting iOS 26, iOS 27.0, and iOS 27.1. The default mode, used before apps are updated for iOS 27.0, places the app in a single view with a safe area surrounded by a black background.

For apps updated to iOS 27, the default mode expands to utilize more of the foldable screen, though some blank space remains. The full compatibility mode, available for apps built with iOS 27.1, takes complete advantage of the iPhone Duo's display, offering the best experience. Apple's own apps and third-party developers aiming for optimal performance will adopt this final mode.

The iPhone Duo launches in October, with iOS 27.1 arriving simultaneously. This phased approach ensures a smooth transition for developers and users alike.