Get your app ready for the iPhone Duo before April 2027.
Until it’s rebuilt, your app opens between black bars on the Duo’s open screen. Apple requires that rebuild for every App Store submission from April onward. It’s also where Flutter and iOS apps run into trouble, from launch crashes to layouts that stretch across the screen. We get your app through it at a fixed fee, and we’ll tell you whether a redesign for the open screen is worth it.
Next is a 30-minute call about your app and what it needs before April.
The iPhone Duo sold out in minutes.
When your users wait months for a release, they notice everything that looks off the day it lands.
- $1,999 starting price Yahoo Finance
- ~10M IDC’s forecast for first-year shipments IDC
- 7.6″ inner display, a small tablet in your users’ hands Apple
- January delivery estimates for preorders placed on launch morning 9to5Mac
What Apple requires from April 2027.
These rules apply to every iOS app you submit, Flutter apps included, whether or not foldables were on your roadmap.
Read Apple’s guidance for the iPhone Duo- 01
Built with the iOS 27 SDK
Every upload, updates included, must be built with the iOS 27 SDK or later. Building with Xcode 27.1 or later is also what removes the black bars. - 02
iPhone Duo screenshots
Every app and game submission must include iPhone Duo screenshots. Apps that add them now get a Duo badge on their App Store product page. - 03
Full-screen layouts
From iOS 27.1, apps fill the whole inner display, and tab bars and toolbars move to the right side. Apps can no longer opt out of full screen.
What Duo owners see when an app isn’t ready.
Apple calls compatibility mode a safety net. To someone who just paid for the open screen, it looks like an app that hasn’t been updated, and that impression shows up in reviews and support tickets.
- Compatibility mode
Black bars on either side
Apps built on the iOS 26 SDK or earlier sit centered on the open display, boxed into a phone-sized window.
- After the rebuild
A phone app on a small tablet
The rebuild fills the screen, and your layout works as it is. Without someone checking it, content can also slide under the status bar or rotate unexpectedly.
- App lifecycle
A crash on launch
An app still on the old app-delegate lifecycle crashes on launch when it’s built with the iOS 27 SDK.
Every iPhone app needs the first tier before April 2027. The other two are your call.
- 01
Duo compliant
The black bars go, and nothing is redesigned. We rebuild on the iOS 27 SDK, migrate to UIScene if your app delegate needs it, fix anything that breaks, and ship the Duo screenshots Apple requires. If App Review rejects the build over Duo layout, we fix it at no cost.
- Starting from
- $5k
- Timeline from
- 3 weeks
Who needs itEvery iPhone app
- 02
Designed for foldables
Everything in Tier 1, plus design and new features made for the open screen: list and detail side by side, layouts that keep off the crease, and a job for each half when it’s half folded. The same work carries over to Android foldables.
- Starting from
- $15k
- Timeline from
- 5 weeks
Who needs itApps people browse, order from, or spend long sessions in
- 03
Designed for every screen
Everything in Tier 2, done for every device your users carry: phones, tablets, foldables, Apple Watch and Wear OS. We also bring Flutter, iOS and your other dependencies up to date, alongside your roadmap, so your team keeps shipping.
- Starting from
- $25k
- Timeline from
- 8 weeks
Who needs itTeams who want one app at home on every device
We already test Flutter and iOS builds on Apple’s Duo simulator.
Flutter apps take most of the rebuild in stride. Fold detection and layouts that feel native on the open screen still take deliberate work, the same as they would in Swift.
Read our engineers’ guide to the iPhone Duo- 01
Flutter and native iOS
Flutter apps are built with Xcode and the iOS SDK, so the same rules apply. We work on both sides every day. - 02
A repeatable test setup
We compare your current build and the rebuilt one side by side, in a clean VM, on Apple’s Duo simulator, before anything ships. - 03
A straight answer first
If your app only needs Apple’s checklist, we’ll say so, and your own team can take it from there. - 04
Built for every screen
Adaptive layouts across phones, tablets, foldables, and wearables are core to how we build.
What teams ask about the Duo.
Short answers from our Duo work so far. Anything else, bring it to the first call.
01 What’s the difference between the three tiers?
Tier 1, Duo compliant, removes the black bars and gets the app through Apple’s April 2027 requirements with no redesign. Tier 2, designed for foldables, adds new design and features for the open screen on the Duo and on Android foldables. Tier 3 does the same for every device your users carry, wearables included, and brings your dependencies up to date alongside your roadmap.
02 What does each tier cost?
Tier 1 starts from $5k, Tier 2 from $15k, and Tier 3 from $25k. The fee is fixed before we start, and depends on the number of screens, how far behind you are on Xcode, Flutter, and plugins, and how much of the design and engineering we own.
03 How long does each tier take?
Starting points are three weeks for Tier 1, five for Tier 2, and eight for Tier 3. Bigger apps and a large wearables build take longer.
04 Do you work on native iOS apps too?
Yes. We build native iOS and Flutter apps, and the Duo rules are the same for both because Flutter apps are built with Xcode and the iOS SDK too. Apple Watch apps are native SwiftUI, and we build those alongside Flutter apps.
05 Why does my app show black bars on the iPhone Duo?
An app built with Xcode 26 opens on the Duo’s inner screen in compatibility mode, with the phone layout in a small centered window and black bars on both sides. Rebuilding with Xcode 27.1 or later removes the bars, and the app fills the inner screen.
06 Do Flutter apps need to adopt UIScene for the iPhone Duo?
Yes, if you build with the iOS 27 SDK. That SDK requires the scene-based lifecycle, and an app still on the app-delegate lifecycle crashes on launch when built with it. Flutter 3.41 migrates apps automatically if the iOS app delegate is untouched. Apps that customized it for push notifications, deep links, analytics, or native code need a manual migration following Flutter’s UIScene guide.
07 When does the App Store start requiring iPhone Duo screenshots?
Starting April 2027, Apple requires every app or game submitted to the App Store to include iPhone Duo screenshots. Rebuilding with Xcode 27.1 or later is what lets those screenshots show your app filling the inner screen instead of sitting between black bars.
08 Can a Flutter app detect the iPhone Duo’s fold?
Not from the framework yet. Fold support on iOS is under review in flutter/flutter #193025. Until it ships, a small native bridge gives a Flutter app the fold, the hinge angle, and the pose, and can be removed once Flutter supports it natively.
09 Does iPhone Duo layout work carry over to other devices?
Largely, yes. The inner screen behaves like a small tablet, so the split views and adaptive navigation built for it carry over to iPad and Android foldables. Watches need their own design, which is what Tier 3 covers.
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