---
title: "iPhone Duo, the foldable iPhone: what changes for your app"
description: "iPhone Duo, the first foldable iPhone, went on sale on October 23, 2026. Your GoodBarber app adapts to both displays after a rebuild: what changes."
canonical_url: "https://www.goodbarber.com/blog/iphone-duo-the-foldable-iphone-what-changes-for-your-app/"
lang: en
date: 2026-10-19
last_updated: 2026-11-05
---

# iPhone Duo, the foldable iPhone: what changes for your app

iPhone Duo, the first foldable iPhone, has been on sale since October 23, 2026. Your GoodBarber app adapts to both of its displays after a rebuild. Here is what your users see, closed and then open, and what you need to do.

![](https://blog.goodbarber.com/_public/profile/65/6553d00ecdbe15f8aac2da7dddcff47648fdd791-default.jpg)

[Mathieu Poli](https://www.goodbarber.com/blog/author/mathieu-poli/)Head of Frontend Engineering

[Select **GoodBarber** as yourPreferred news sourceSelect **GoodBarber** as your](https://www.google.com/preferences/source?q=goodbarber.com)

Oct 19, 2026 · Updated Nov 5, 2026 · 7 min read

![](https://cmsphoto.ww-cdn.com/superstatic/41269/art/grande/98426413-68696825.jpg?v=1793091983.2110784)

[A GoodBarber app on iPhone Duo, closed then open](https://player.vimeo.com/video/1239769318?badge=0&autopause=0&player_id=0&app_id=58479&title=0&byline=0&portrait=0&dnt=1)

*A GoodBarber app on iPhone Duo, closed then open: the bars move into a rail, and grids gain a column.*

## What changes with iPhone Duo?

iPhone Duo, [the first foldable iPhone](https://www.apple.com/newsroom/2026/10/iphone-duo-arrives-at-apple-store-locations-worldwide/), has two displays. When it is closed, you use the outer display, held upright or sideways; it is wider and shorter than the display on other iPhone models. Open, you get a large inner display, which can also be held either way, flat or partially folded like a book.

Apple moves the bars to the side. Its [design guidelines for iPhone Duo](https://developer.apple.com/design/human-interface-guidelines/designing-for-iphone-duo) put it this way: on the outer display, "the system places toolbars and tab bars on the side to maximize the vertical space for content." This is the most visible change for an app.

## What does your app look like when iPhone Duo is closed?

[iPhone Duo closed, held upright, with the Long Light app and its column of icons on the right](https://player.vimeo.com/video/1239776226?badge=0&autopause=0&player_id=0&app_id=58479&autoplay=1&muted=1&loop=1&title=0&byline=0&portrait=0&dnt=1)

*Closed: the search icon and the tabs move into the rail, along the edge of the display. Long Light, a demo app.*

Your app keeps its phone layout: the same home screen and the same content, at the same text sizes. What changes is where the controls sit. The back button, the shortcuts from the top bar and the actions of a detail page move into a vertical column along the edge of the display. This column, the rail, holds icons only. Depending on its style, your [tab bar](https://www.goodbarber.com/blog/item-the-element-that-shapes-every-tab-in-your-app-a1624/) moves there too or stays at the bottom of the display: a text-only tab bar, for example, stays at the bottom. The title, the logo, the search field and text buttons stay at the top, as they do now.

When height runs short, the rail condenses: a group of tabs or actions collapses into a single icon, which a tap opens again. No control goes under the camera, and what floats above the content, like the audio player or the [global floating button](https://www.goodbarber.com/blog/a-global-floating-button-one-key-action-visible-everywhere-in-your-app-a1524/), stays in the content area.

Turn the closed iPhone Duo sideways and your app turns with it: lists and grids spread across the width. This rotation is specific to iPhone Duo; on other iPhone models, your app stays in portrait, as it does today.

## What does your app look like when iPhone Duo is open?

[iPhone Duo open, with the Long Light front page across the full width](https://player.vimeo.com/video/1239776227?badge=0&autopause=0&player_id=0&app_id=58479&autoplay=1&muted=1&loop=1&title=0&byline=0&portrait=0&dnt=1)

*Open, the front page becomes a spread. Long Light, a demo app.*

On the large display, your app does not get bigger. Text sizes and margins stay the same as on the phone; the extra width shows more items side by side. A list moves from one column to two, and a grid of small cards goes up to four columns when the open iPhone Duo is held sideways. Article pages keep their text in a comfortable reading column, 535 points wide at most, while the image spans the whole display.

Held sideways, the open iPhone Duo keeps the rail on the side, so the controls stay in the same place as you move from one display to the other. Held upright, it has enough height for standard bars, at the top and at the bottom.

[iPhone Duo opening while The Current app plays a podcast](https://player.vimeo.com/video/1239776225?badge=0&autopause=0&player_id=0&app_id=58479&autoplay=1&muted=1&loop=1&title=0&byline=0&portrait=0&dnt=1)

*The podcast keeps playing while the phone opens. The Current, a demo app.*

## Do you need to redesign your app for iPhone Duo?

[The Eastside Music Workshop app on iPhone Duo, with its sections and its tab bar](https://player.vimeo.com/video/1239776228?badge=0&autopause=0&player_id=0&app_id=58479&autoplay=1&muted=1&loop=1&title=0&byline=0&portrait=0&dnt=1)

*The same app keeps its design and its sections; only the layout follows the display. Eastside Music Workshop, a demo app.*

No. There is no option to switch on and no screen to design. Every GoodBarber app is built from the same families of screens: lists, grids, detail pages, and full-screen views like a map or a player. We wrote the adaptation rules once for each of them, and every app inherits them while keeping its own sections and design. These rules build on [DuoApps](https://www.duoapps.com/), the open knowledge base our design team publishes on designing apps for iPhone Duo.

A native app builder like GoodBarber produces all of its [native apps](https://www.goodbarber.com/glossary/native-app/), [compiled in Swift for iOS](https://www.goodbarber.com/native/technology/), with a shared engine: a new iOS feature is handled there once, then each app receives it when it is rebuilt.

## What do you need to do so your app takes advantage of iPhone Duo?

[The publishing panel of the back office, with the rebuild button for the iOS app](https://player.vimeo.com/video/1239776240?badge=0&autopause=0&player_id=0&app_id=58479&autoplay=1&muted=1&loop=1&title=0&byline=0&portrait=0&dnt=1)

*In the back office, the iOS app shows that a rebuild is needed.*

Run a rebuild of your iOS app from the back office. If you wait, your app gets this adaptation at its next build, as with [each new version of iOS](https://www.goodbarber.com/blog/do-i-need-to-update-my-app-for-a-new-ios-or-android-a1575/). Until then, it opens on iPhone Duo without using the whole display: [Apple notes](https://developer.apple.com/documentation/technologyoverviews/preparing-your-app-for-iphone-duo) that an app built with Xcode 26 or earlier doesn't extend under the status bar and the camera.

## Frequently asked questions

**Is my GoodBarber app compatible with iPhone Duo?**

Yes. Like any app, it opens on iPhone Duo. After a rebuild of your iOS app, a app adapts to both displays of iPhone Duo, closed or open, upright or sideways. There is nothing to set up and nothing extra to design.

**What do my users see if I don't run a rebuild?**

Your app opens on iPhone Duo, but without using the whole display: [Apple notes](https://developer.apple.com/documentation/technologyoverviews/preparing-your-app-for-iphone-duo) that an app built with Xcode 26 or earlier doesn't extend under the status bar and the camera. On the open iPhone Duo, such an app appears in the center of the display, with empty space around it, [as Apple shows](https://developer.apple.com/iphone-duo/prepare/). The rebuild gives it the whole display and the adapted layout.

**Do I need to design specific screens for iPhone Duo?**

No. Your app keeps its design and its sections, and adapts its layout to the shape of the display. On the closed iPhone Duo, most of its controls move into a column of icons along the edge of the display; on the open one, it shows more items side by side.

**Does my app change on iPad or on other iPhone models?**

No. Nothing changes on iPad. On other iPhone models, your app stays in portrait, as it does today: rotation is specific to iPhone Duo.

**Do I need new App Store screenshots?**

Not before April 2027. Apple [will then require iPhone Duo screenshots](https://developer.apple.com/help/app-store-connect/reference/app-information/screenshot-specifications/) for any app built with the iOS 27.1 SDK or later. Once you add them, your App Store product page shows the [Made for iPhone Duo badge](https://www.apple.com/newsroom/2026/10/developers-bring-incredible-new-app-experiences-to-iphone-duo/), telling people your app is optimized for iPhone Duo.

## Going further

The rules we started from, with their sources and demos, are freely available on [DuoApps](https://www.duoapps.com/), reusable with credit (CC BY 4.0 license).

To give your users the iPhone Duo layout, run a rebuild of your iOS app from the back office.

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About the author

Mathieu Poli

Head of Frontend Engineering

I'm am Head of Frontend Engineering at GoodBarber.

I oversee the teams that build the rendering engines at the core of our no-code platform: they're what bring our users' projects to life and turn them into native apps that are smooth and polished. Everything you see and interact with on screen passes through their hands.
A pioneer of mobile no-code, passionate about software architecture and product design, I also teach in universities and private schools.

Here, I write about frontend engineering, product design and AI — and everything that happens when those three worlds meet.

[More from Mathieu](https://www.goodbarber.com/blog/author/mathieu-poli/)[LinkedIn](https://www.linkedin.com/in/hellomathieup)[X](https://x.com/hellomathieup/)