Apple has released the first beta of Xcode 27.1, giving developers the tools needed to build, run and test apps for iPhone Duo ahead of the foldable iPhone’s October 23 launch.
The beta includes updated SDKs and an iPhone Duo simulator capable of reproducing the device’s different poses and orientations. Developers can use Device Hub to open, close, rotate and fold a simulated iPhone Duo while checking how their apps respond to changes between its displays.
Apple says existing apps will continue to work on iPhone Duo even if they were not built using the iOS 27 SDK. Apps built with iOS 27 gain better resizing behavior, while building against the iOS 27.1 SDK allows an app to take advantage of the full available screen space.
The additional testing is particularly important because iPhone Duo introduces layouts that conventional iPhones do not need to handle. Apps can move between the outer and inner displays, resize as the device opens or closes, and run in different orientations and Split View configurations.
Apple is encouraging developers to use flexible layouts and size classes rather than making assumptions based on fixed display dimensions or interface orientation. Standard SwiftUI and UIKit components including TabView, NavigationSplitView and their UIKit equivalents can automatically adapt as the available space changes.
Xcode 27.1 also lets developers preview content on alternative displays through Xcode’s canvas, helping them account for the different ways an app can appear across iPhone Duo’s screens.
The release gives developers just over a month to optimize their apps before iPhone Duo reaches customers on October 23. Apple has also opened workshops, Group Labs and developer Q&A sessions focused on designing and building apps for the new form factor.
TestFlight now accepts apps built using Xcode 27.1 beta and the iOS 27.1 beta SDK for internal and external testing, allowing developers to begin distributing iPhone Duo builds to testers ahead of launch.
Apple announced iPhone Duo earlier this month as its first foldable iPhone. The device will ship with iOS 27.1, which includes features developed specifically for its foldable design.