Skip to content
duoapps
  • Audit
  • Adapt
  • Build
  • Ship

Apps that
unfold.

We adapt existing iOS apps and build new ones for iPhone Duo, so your app looks designed for both displays, not stretched across them.

Book a Duo auditSee what changes
Outer display · 5.4″

  1. 01 / 05Closed

    Folded, it’s a 5.4″ iPhone.

    Closed, iPhone Duo is a compact iPhone with a 5.4″ outer display. Your app needs to feel at home here first.

  2. 02 / 05Open

    Open it, and there’s 7.6″ to fill.

    The inner display opens like a book. Apple says it’s 50% larger than the iPhone 18 Pro Max display.

  3. 03 / 05Not adapted

    Unadapted apps get empty margins.

    An app that hasn’t been adapted runs as a narrow column, with empty space on either side.

  4. 04 / 05Adapted

    Great apps use every pixel.

    List and detail side by side, with your place kept as it folds and unfolds. This is what we build.

  5. 05 / 05Split View

    Two apps. One screen.

    iOS 27 brings Split View to iPhone for the first time. Your app has to look right at every width.

iPhone Duo went on sale Source (Apple Newsroom, opens in a new tab)
Oct 23, 2026
Inner and outer displays, same aspect ratio Source (Apple Newsroom, opens in a new tab)
7.6″ + 5.4″
Side by side in Split View, a first for iPhone Source (Apple Newsroom, opens in a new tab)
2 apps
Ships on every iPhone Duo Source (Apple Newsroom, opens in a new tab)
iOS 27.1

The gap

Most apps just get bigger.
Great ones get better.

iPhone apps run on iPhone Duo without changes. But an app that hasn’t been adapted shows up as a narrow column on a wide 7.6″ display, with empty space on either side. It works. It just looks unfinished on a phone that starts at $1,999.

“There are a ton of apps that haven’t been optimized yet to run on a device like this.”
- Engadget (opens in a new tab), iPhone Duo review
Not adapted

A portrait column with dead space on both sides.

Duo-native

List and detail side by side, using the whole display.

Services

Everything your app needs
for the fold.

  • Duo Readiness Audit

    We test your current build on both displays (folded, unfolded, rotated, and in Split View) and hand you a prioritized fix list with effort estimates.

  • App adaptation

    Layouts that reflow across the fold, list-and-detail panes on the inner display, Split View support, and state that survives folding.

  • Duo-first new builds

    Native Swift and SwiftUI apps designed for the outer and inner display from the first wireframe.

  • Paywalls & onboarding

    Two-column paywalls and onboarding built for the large display, with every call to action kept clear of the fold.

  • App Store assets

    Screenshots and previews that show your app at its best on both displays.

  • Ongoing iOS support

    We keep your app current as Apple ships iOS updates and new APIs for iPhone Duo.

What changes

One phone.
Two screens. Every posture.

Here’s what we check and fix in every engagement. Each item comes from how Apple says iPhone Duo and iOS 27 work.

Read Apple’s announcement (opens in a new tab)

  1. 1. Layouts for both displays

    The 5.4″ outer and 7.6″ inner displays need their own layouts, not one stretched across both.

  2. 2. Fold continuity

    iOS reflows content as iPhone Duo folds and unfolds. Your app should keep scroll position, drafts, and playback through the transition.

  3. 3. Split View & multiple windows

    People can run two apps side by side, open two windows of the same app, and save app pairs. Your app has to look right at every width.

  4. 4. Controls on the side

    On iPhone Duo the Dock and app controls move to the side, and the Dynamic Island runs vertically. Custom bars and overlays have to respect that.

  5. 5. Touch ID, not Face ID

    iPhone Duo authenticates with Touch ID in the side button. Hard-coded “Face ID” wording and flows need updating.

  6. 6. Under-display camera

    The inner display has a FaceTime camera under the screen. Video, camera, and AR experiences need to account for it.

Process

From audit to App Store
in four steps.

  1. 01

    Audit

    We run your app on iPhone Duo and send a written report: what breaks, what looks unfinished, and what to build first.

    About 1 week

  2. 02

    Plan

    Wireframes for the outer display, the inner display, and Split View, with a fixed scope and timeline.

    1–2 weeks

  3. 03

    Adapt or build

    Weekly TestFlight builds you can install and review on your own device.

    Depends on scope

  4. 04

    Ship & support

    App Store submission, release, and follow-up fixes as iOS updates land.

    Ongoing

Engagements

Start small.
Scale when it’s worth it.

Every engagement starts with an audit, so you know exactly what you’re paying for before any build work begins.

  • Readiness Audit

    For teams with a live iOS app

    Fixed fee

    About 1 week

    • Testing on iPhone Duo in every posture
    • Screen-by-screen report with screenshots
    • Prioritized fix list with effort estimates
    • 60-minute walkthrough call
    Book an audit
  • Recommended

    Duo Adaptation

    Make your existing app feel native

    Quoted after the audit

    Typically 3–8 weeks

    • Everything in the audit
    • Adaptive layouts for both displays
    • Split View and multi-window support
    • Fold continuity for state and media
    • Touch ID and side-control fixes
    • App Store screenshots for both displays
    Start with an audit

  • Duo-first Build

    A new app designed for iPhone Duo

    Custom quote

    Typically 3–6 months

    • Product strategy and design for both displays
    • Native Swift and SwiftUI
    • Backend, APIs, and integrations
    • Launch, App Store review, and support
    Talk to us

Launch partners

Be one of the first
Duo-native apps.

We’re taking on a small first group of apps. You get priority scheduling. With your sign-off, we publish the before-and-after as a case study.

  • Priority scheduling
  • Before-and-after case study
  • You approve everything we publish
Apply to be a launch partner

FAQ

Questions,
answered.

Will my app run on iPhone Duo without changes?

Yes. iPhone apps run on iPhone Duo. But an app that hasn’t been adapted can appear as a portrait column with empty space on either side of the inner display, or with letterboxing. It works, but it looks unfinished, and that’s what we fix.

What does it cost?

Every app is different, so we quote adaptation and build work after the audit. The audit is a fixed fee, and the report is yours to keep whether or not you hire us for the rest.

How long does it take?

The audit takes about a week. Adapting an existing app typically takes 3–8 weeks, and new apps take longer. You get a firm timeline with your quote.

Native or cross-platform?

We build new apps natively in Swift and SwiftUI, which gets Apple’s newest iPhone Duo APIs first. If your app is built with React Native or Flutter, the audit tells you what can be adapted now and what depends on framework support.

Do you need our source code?

Not for the audit. A TestFlight or App Store build is enough. For adaptation work we work in your repository, and we’re happy to sign an NDA.

Who owns the code?

You do. Everything we write for you belongs to you.

Are you affiliated with Apple?

No. duoapps is an independent studio. iPhone and iPhone Duo are trademarks of Apple Inc.

Let’s make your app
unfold.

Tell us about your app. We reply within one business day.

Email us

hello@duoapps.dev