Your test tools
| Tool | Good for | Misses |
|---|---|---|
| Resizable iOS simulator (Device Hub) | Quick checks of layout across sizes | Vertical bars, reserved regions, the hinge |
| iPhone Mirroring on macOS 27 | Dragging your real app to extreme sizes in both directions | Vertical bars, reserved regions, the hinge |
| iPhone Duo simulator (Xcode 27.1) | The full experience: open, close, rotate, fold, Split View | Feel: reachability, weight, real touch |
| A physical iPhone Duo | Touch targets, reachability, asymmetric safe areas in the hand |
Apple’s engineers recommend validating touch targets, vertical bar placement and navigation on a real device before shipping, because the simulator can feel different. If you don’t have one, Apple runs iPhone Duo workshops through Meet with Apple, though devices aren’t available at every location.4
A pose-by-pose test plan
Run each step in the iPhone Duo simulator, and repeat the ones that matter on a device:
- Closed, portrait and landscape. Bars should be vertical along the side, with nothing under the camera or status bar. Check overflow in landscape, where vertical space is shortest.
- Open, portrait and landscape. Your regular width and height layout: sidebars, multiple columns, nothing stretched or awkwardly centered. Bars are horizontal in portrait and vertical in landscape.
- Partly folded (book and table). Nothing important spans the fold. Alerts and popovers clear it.
- Fold and unfold in the middle of a task. Type text, scroll, play video and start editing, then change pose. Everything should survive, with no relaunch and no lost input.
- Split View on the inner display. Drag your app by the home indicator to one side, then the other. Check the safe area on both edges.
- Inner camera on. If your app uses the front camera, check that custom controls stay clear of it.
- Dynamic Type at accessibility sizes, in at least the closed and open poses.
- Right-to-left language. The vertical bar stays on the same side of the hardware; your content should mirror around it.1
App Store screenshots
From App Store Connect’s screenshot specifications:
| Display | Portrait | Landscape |
|---|---|---|
| Outer | 1398 × 2034 px | 2034 × 1398 px |
| Inner | 2007 × 2853 px | 2853 × 2007 px |
When you submit iPhone Duo screenshots, your product page shows a badge saying the app is optimized for iPhone Duo.2 They’re optional for now. Apple’s announcement says iPhone Duo screenshots will be required for submissions starting in April 2027, and the screenshot specification page says the requirement applies to apps using the iOS 27.1 SDK or later.23
Apple also suggests:
- Showing your app in several orientations and poses in previews and screenshots.
- Checking every asset, including the new product page headers and search result assets, in App Store Connect’s new preview tool.5
- Nominating your app for featuring in App Store Connect. In the Helpful Details section, say that it’s optimized for iPhone Duo and supports all poses.2
Shipping notes
- iPhone Duo-only apps aren’t allowed. You’re still shipping an iPhone app, so you don’t need new required device capabilities.4
- iPad support isn’t required, though an iPad layout gives you a head start on the inner display.
- Keep your deployment target. Gate iOS 27.1 APIs with
#available(iOS 27.1, *)and fall back to size-class-driven layout on older systems.1 - Remove
UIRequiresFullScreenif you still have it. It’s deprecated, and iPhone Duo resizes your app when it opens or closes anyway.1
Tell people
Once your update is live, let your users know, and send us a report so your app’s page on Fits Duo shows it as optimized.