Xcode 27.1 or later. It includes the iPhone Duo simulator, which runs inside Device Hub, and the SDK that lets your app reach the screen edge. Apple’s Tech Talks describe Device Hub controls to open, close, rotate and fold the simulated device.
Xcode 27.1 also renames the app modernization skill, introduced in the WWDC26 talk “Modernize your UIKit app”, to App Resizability, and extends it to SwiftUI and iPhone Duo.
Apple released Xcode 27.1 beta (build 27A9269) on 18 September 2026. It needs a Mac running macOS Tahoe 26.6 or later. Build and test with it now, but keep shipping with your release Xcode: App Store submissions need the final version, which Apple has not dated yet. Current status, requirements and known issues.
Apple published the written Preparing your app for iPhone Duo guide the same day, alongside the Designing for iPhone Duo Human Interface Guidelines page. Between them they now cover the API surface the six Tech Talks introduced.
Where the simulator comes from
Apple’s release notes describe it as the iPhone Duo Simulator runtime in Xcode 27.1 beta. Choose an iPhone Duo run destination; if Xcode does not list one, check Xcode > Settings > Components, where Xcode lists the simulator runtimes it can download. Apple’s iPhone Duo page points developers to Xcode 27.1 beta for the SDKs to build, run and test for iPhone Duo.
What the beta can and cannot test yet: Xcode 27.1 beta is out.