Two weeks after its launch, Apple’s iPhone Duo foldable has already reached a major milestone: over 100,000 apps on the App Store are built specifically for the device. The figure, announced by Apple’s VP of Worldwide Developer Relations Susan Prescott, reflects apps that use the iOS 27.1 SDK or later and display correctly on both the inner and outer screens. While the number is impressive, it also highlights which popular services still lag behind.
Key takeaways
- Apple reports "well over 100,000" iPhone Duo‑optimized apps, with thousands added daily.
- Optimization requires the iOS 27.1 SDK or later; older apps appear centered with black bars.
- Apple provides a "Made for iPhone Duo" badge to help users spot optimized apps.
- Major apps like Excel, Zoom, and Netflix are already optimized, but many everyday services (e.g., YouTube Music, Amazon Fire TV) are not.
- Developers can attend workshops or use SwiftUI/UIKit components for automatic adaptation.
How apps get the "Made for iPhone Duo" badge
Apple defines a Duo‑optimized app as one built with the iOS 27.1 SDK (or newer). Those apps fill the full width of both displays and shift controls to a vertical status bar, allowing seamless use in the device’s various folding positions. In the App Store, such apps display a distinctive "Made for iPhone Duo" badge, making them easy to spot on the device.
Examples of optimized apps
Apple highlighted a mix of productivity, entertainment, and social apps that have already been updated. Below is a snapshot of some notable examples:
| Category | App |
|---|---|
| Productivity | Microsoft Excel, Word, PowerPoint, OneNote |
| Communication | Zoom, WhatsApp, Microsoft Teams |
| Entertainment | Netflix, YouTube, Amazon Prime Video, NBA app |
| Creativity | Halide Mark III, Procreate Pocket |
| Shopping & Services | Etsy, Goodnotes, Fantastical, Flighty |
What’s still missing?
Despite the large catalog, many widely used apps remain unoptimized. Apple listed dozens that still run in the legacy mode, appearing centered with empty space on either side. The list includes:
- Amazon Fire TV, YouTube Music
- Google Docs, Sheets, Slides
- DoorDash, Uber Eats, GrubHub
- Spotify, Steam, Whole Foods
- Various airline and ticketing apps such as Delta and JetBlue
These apps still function on the Duo but do not take full advantage of the dual‑screen layout.
Why the optimization matters
When an app is built for the iPhone Duo, it automatically adapts to the device’s unique form factor. Users enjoy:
- Full‑screen use on the inner display without black bars.
- Vertical status‑bar controls that keep navigation consistent when the device is folded.
- Multi‑column layouts that can show more information simultaneously (e.g., a chat list on one pane and a conversation on the other).
Non‑optimized apps, while still usable, often feel cramped or require extra tapping to switch between screens, diminishing the foldable’s advantage.
What this means for you
If you already own an iPhone Duo, you can quickly check whether an app is Duo‑ready:
- Open the App Store on your Duo.
- Search for the app and look for the "Made for iPhone Duo" badge under the app name.
- Install the badge‑ed version for the best experience.
For apps that lack the badge, you can still download them, but expect the centered display with black borders. Keep an eye on app updates; many developers roll out Duo‑specific improvements weeks after the initial release.
How developers can join the foldable wave
Apple says thousands of developers have attended workshops in 19 cities worldwide, learning hands‑on how to adapt their code. The core advice:
- Use standard SwiftUI and UIKit components; they automatically resize for both displays.
- Leverage the new iOS 27 APIs that expose layout information for the inner and outer screens.
- Add the "Made for iPhone Duo" badge in App Store Connect once the app meets the criteria.
Apple also provides online resources, including the Apple Developer Forums and documentation, to help smaller teams get started.
What happens next?
Apple expects the daily addition of Duo‑optimized apps to continue accelerating as more developers adopt the iOS 27.1 SDK. Future iOS updates are likely to introduce even richer APIs for multi‑window and multi‑tasking scenarios, further differentiating the Duo from traditional smartphones.
Consumers should expect a growing selection of fully‑optimized experiences, especially in productivity, gaming, and media. Meanwhile, the list of unoptimized apps will shrink as developers prioritize the badge to stay competitive on Apple’s foldable platform.
Conclusion
The 100,000‑app milestone shows that Apple’s developer ecosystem is responding quickly to the iPhone Duo’s unique hardware. While the badge makes it easy to find the best apps, users will still encounter a handful of popular services that lag behind. By staying aware of the badge and checking for updates, Duo owners can make the most of the device’s dual‑screen potential.
Frequently asked questions
How can I tell if an app is optimized for iPhone Duo?
Look for the "Made for iPhone Duo" badge in the App Store listing on your device.
Do non‑optimized apps still work on the iPhone Duo?
Yes, they run but appear centered with black bars on the inner screen.
What SDK version is required for iPhone Duo optimization?
Apps must be built with the iOS 27.1 SDK or later.
Are there tools for developers to make apps Duo‑ready?
Apple recommends using standard SwiftUI or UIKit components and its new iOS 27 APIs.
Which popular apps are still not optimized for iPhone Duo?
Examples include YouTube Music, Amazon Fire TV, Google Docs, DoorDash, and Steam.
