Split View on the iPhone Duo runs two apps side by side on the 7.6-inch inner display, and the apps have to be built to resize for it. Apple published six developer sessions and four dated events for that work on September 9, and listed the Xcode 27.1 beta needed to build for the phone as coming later this month.
That gap is the story. The Duo goes on sale Friday, October 23, so the window between the software development kit appearing and the phone reaching buyers is roughly five weeks at best, and Apple has published no list of apps that are ready.
Key facts on iPhone Duo app support
| Item | What Apple publishes |
|---|---|
| Split View | Two apps side by side on the inner display |
| Developer guidance | Build apps with dynamic resizing and adaptive layouts |
| Sessions published | Six, on September 9 |
| Live documentation | “Designing for iPhone Duo” in the Human Interface Guidelines |
| Written guide | “Preparing your app for iPhone Duo,” coming later this month |
| Xcode 27.1 beta | Coming later this month |
| Newest shipped Xcode | Xcode 27 RC, build 27A266a, September 9 |
| Compatible app list | Not published |
What Apple says Split View is
Apple’s description is deliberately narrow: two apps side by side on the inner display. It does not describe a third app, a slide-over panel, a floating window or a resizable divider, and it does not say what happens to the pair when the phone is folded shut.
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The rest of the Duo software list that ships with it is short as well, covering an upgraded StandBy, a redesigned Dynamic Island and a Call Context widget, all on iOS 27.1 rather than the iOS 27 that other iPhones get on Monday, September 14.
The six sessions Apple published on day one
The sessions are the most detailed public account of the Duo’s software behavior, and their titles map neatly onto the features Apple sells on the product page.
- Design for iPhone Duo
- Prepare your app for iPhone Duo
- Raise the bar with iPhone Duo
- Strike a pose with adaptive layouts on iPhone Duo
- Leverage multiple displays and scenes on iPhone Duo
- Build a great camera experience for iPhone Duo
Two of those titles confirm something the consumer pages only imply, which is that the fold is treated as multiple displays and scenes rather than one screen that changes size, and that pose is a state an app is expected to respond to.
Four dates on Apple’s developer calendar
| Date | Event | Times (PT) |
|---|---|---|
| Wednesday, September 16 | iPhone Duo Group Lab | 8 p.m. to 9 p.m. |
| Thursday, September 17 | iPhone Duo Group Lab | 8 a.m. to 9 a.m. |
| Wednesday, September 23 | Photos and Camera Q and A | 7 a.m. to 9 a.m., 6 p.m. to 8 p.m. |
| Wednesday, September 23 | SwiftUI Q and A | 8 a.m. to 10 a.m., 5 p.m. to 7 p.m. |
| Wednesday, September 23 | UIKit Q and A | 8 a.m. to 10 a.m., 5 p.m. to 7 p.m. |
| Later this month | iPhone Duo workshops | No date published |
Apple also carries a forward requirement from the same developer post: from April 2027, apps uploaded to App Store Connect must be built with the iOS 27 and iPadOS 27 software development kit or later. As of Friday, September 11, no iOS 27.1 build had appeared on Apple’s developer releases page, where the newest iOS 27 row was still the 27.0 release candidate.
The apps Apple showed, and what they do not prove
Apple’s own iPhone Duo images put named third-party apps on the inner display, including Safari alongside the Siri app in Split View, plus Netflix, Slack, Zoom and Detail running full width.
Those images are marketing, not a compatibility statement. Apple has published no list of apps that support Split View, no list that has been updated for the fold, and no way for a buyer to check before ordering. The Duo against the iPhone 18 Pro Max comparison is where the hardware differences sit; app readiness is a separate question Apple has left open.
What Apple has not said
- When the Xcode 27.1 beta and the written guide arrive, beyond later this month
- When a Duo simulator becomes available to developers who do not have the phone
- The display point sizes, safe areas or new API names apps will be built against
- Which apps support Split View, and how an unmodified app behaves on the inner display
- Whether Split View can hold more than the two apps Apple describes
- Whether the camera sessions imply third-party access to Duo Preview, Kid Cue or the outer display
Apple’s two Group Labs run on Wednesday, September 16 and Thursday, September 17, with three Q and A tracks on Wednesday, September 23. iPhone Duo pre-orders open Friday, October 16 at 5 a.m. PT and the phone goes on sale Friday, October 23. Our event recap covers everything else Apple announced.
