Xcode 27.1 RC opens the App Store to iPhone Duo apps

Apple started accepting App Store submissions for iPhone Duo apps on October 5, 2026, and released the Xcode 27.1 Release Candidate to build them. The foldable iPhone reaches customers on October 23, according to Apple's developer news. That gives app teams 18 days to ship a build that handles a phone that folds before the first buyers open their apps.

What Apple opened on October 5

Xcode is Apple's app for building iPhone and Mac software. A Release Candidate, or RC, is the build Apple expects to ship as final unless a serious bug turns up. 9to5Mac reports that Xcode 27.1 RC 1 is now available for download.

Apple's notice lists several pieces that arrive together:

• Apps built or recompiled with Xcode 27.1 get a badge on the App Store, 9to5Mac reports.
• App Store Connect, the portal where developers manage listings, adds a preview tool for checking assets on iPhone Duo.
• Figma and Sketch design kits for iPhone Duo are available from Apple Design Resources.
• Developers can register for in-person iPhone Duo workshops.

There is also a firm deadline. Apps submitted after April 2027 must include screenshots for iPhone Duo, according to both Apple and 9to5Mac.

Date	What happens	Source
September 18, 2026	Xcode 27.1 beta ships with Device Hub	Apple
October 5, 2026	Xcode 27.1 RC 1; submissions open	Apple, 9to5Mac
October 12, 2026	Pre-order registration opens	9to5Mac
October 16, 2026	Pre-orders begin	9to5Mac
October 23, 2026	iPhone Duo reaches customers	Apple
April 2027	Duo screenshots required for new submissions	Apple

How Device Hub tests a folding phone

Device Hub is the Xcode 27.1 tool for trying an app on a simulated iPhone Duo. Apple says it shows "how your apps behave on iPhone Duo across all poses and orientations." A pose is the physical position of the phone, such as folded shut or opened flat.

The Apple Post describes the hands-on side. Developers can "open, close, rotate and fold a simulated iPhone Duo" while they watch how the app moves between its displays. That matters because a fold changes the screen size while the app is running.

Apple's own layout building blocks do part of the work. The Apple Post reports that standard SwiftUI components adapt on their own as the available space changes. It names TabView, the container behind a tab bar, and NavigationSplitView, the layout with a sidebar beside a detail view. Custom layouts get no such help.

Testing started earlier than the store opening. TestFlight, Apple's beta-testing service, has accepted iPhone Duo builds for more than a month, The Apple Post says. MacTrast reports that Xcode 27.1 needs an Apple silicon Mac running macOS 26.6 or later.

Why the rebuild matters before launch day

The badge rewards teams that move early. Only apps built or recompiled with Xcode 27.1 carry it, so an app that skips the update looks unprepared next to rivals on day one.

The stakes come from the hardware. When Apple announced the iPhone Duo alongside the iPhone 18 Pro in September, the developer question was whether layouts would survive a fold. This site has since covered the Duo's replaceable screen cover layer. Now the software deadline is fixed as well.

What this means for developers

Download the Xcode 27.1 RC this week and confirm your build Macs run macOS 26.6 or later. A team still on an older macOS needs that upgrade first, so schedule it before the code work.

Then open every main screen in Device Hub and walk it through each pose. Look for anything that assumes one fixed screen shape. Hardcoded widths, fixed aspect ratios and custom split views are the usual suspects. Screens built on TabView and NavigationSplitView should need less work, so spend your testing time on custom layouts.

Aim to submit before October 23. Buyers who pre-order are likely to install apps on launch day, and the badge is how they will spot ready apps. Push a TestFlight build to anyone on your team who has ordered the device.

Finally, put April 2027 on the release calendar. Every submission after that date needs iPhone Duo screenshots. Use the new App Store Connect preview tool to check how your listing looks on the device before then.