iPhone Duo, Day Two: The Assets That Appeared in 24 Hours

What appeared for iPhone Duo in the 24 hours after the keynote? From Apple, a product-bezel pack on the Design Resources page and iPhone Duo rows in App Store Connect’s screenshot and app-preview specifications, added the afternoon of the keynote. Their inner-display size, 2853 by 2007 pixels, implies 669 by 951 points at an assumed 3x scale rather than the 626 by 890 the spec sheet’s panel implied, and the bezel pack’s own screen cutout corroborates it.¹³¹⁷ From everyone else, 37 GitHub repositories, led by a Three.js fold study on Apple’s 3D model, a 12-example SwiftUI kit, and seven repositories of agent instructions; Mastodon posts from indie developers asking three questions; and still no Xcode 27.1 beta, no “Preparing your app for iPhone Duo” guide, and no API documentation.^4581011

This post is the day-two companion to the live event post, the developer post, and the design post. Those three read Apple’s material. This one reads what appeared around it between the keynote and about 10:45 a.m. PT on September 10, with a judgment on each item: an asset you can use today, a question worth answering, or noise.

TL;DR: Use Apple’s bezels to show your app in mock-ups and marketing, under Apple’s terms, and keep the community’s 3D fold studies out of marketing, which Apple’s guidelines forbid.² Read App Store Connect’s screenshot row as the first point-size evidence Apple has published, on an assumed 3x scale, and redo any arithmetic built on 626 by 890.³ Treat the community code as sketches: none of it compiles against the Duo APIs, because the SDK that has them is still marked as coming later this month, and every repository that names an API took the name from a talk’s narration or on-page code snippet, not from a header.⁴⁸¹⁰ The three questions developers are asking, where the simulator is, what an un-adapted app looks like, and how state survives the fold, have one Apple answer, one answer in the talks that nobody can test yet, and no answer yet.¹¹

Frame from Apple’s September 9, 2026 event stream, 11:15 a.m. PT: the iPhone Duo recap slide. Everything Apple and the community built in this post arrived after it.

From Apple: bezels and submission specifications

The bezel pack. Apple’s Design Resources page now lists iPhone Duo under Product Bezels, with one download, “Photoshop, PNG,” beside iPhone 18, iPhone 17, and the iPads.¹ The disk image holds 10 layered Photoshop files and 10 flat PNGs: two finishes, Night Sky and Star White, in five poses each, the inner display open in landscape and in portrait, the outer display closed in landscape and in portrait, and the open device seen from the outside with the outer display’s cutout on one half.¹

What the cutouts say. The inner-display frames are 3093 by 2247 pixels around a 2853 by 2007 screen cutout with a 120-pixel border on every side; the closed-portrait frame is 1574 by 2194 around a cutout 1398 pixels wide. The outer cutout measures 1398 by 2032 fully transparent pixels plus a near-transparent row at top and bottom, 1398 by 2034 in all, the panel’s own count. The inner screen is another matter: 2853 by 2007 is App Store Connect’s inner-display screenshot size to the pixel, 951 by 669 points at 3x, so a native-resolution 2670 by 1878 capture needs scaling to fit, and the bezel pack corroborates the same dimensions.¹³

What you may do with them. The license in the image is the standard one for Apple’s design resources, which limits the files to mock-ups of software that runs on Apple’s platforms, and Apple’s App Store Marketing Guidelines say to “Use Apple-provided product bezels in all your marketing materials to display your app on the Apple devices it supports.” The same guidelines list what is not permitted in marketing materials, starting with “Rendering in 3D or creating any simulation of an Apple product.”² So the pack is for showing your app on the device, in a mock-up or in your marketing; the 3D studies below are not.

What is missing. There is no Figma or Sketch file for iPhone Duo on the page; the iOS 27 and iPadOS 27 UI Kit is listed for both tools, the Duo bezels for Photoshop only.¹

The screenshot sizes. App Store Connect’s screenshot specifications carry an iPhone Duo row: 1398 by 2034 pixels for the outer display and 2007 by 2853 pixels for the inner display, each in both orientations. App Store Connect’s release notes date the addition to September 9, and Apple’s releases feed stamps that update 3:00 p.m. PT; my own fetch of the page that afternoon had followed a redirect badly and missed it, and I first saw the row on the morning of September 10.³¹⁸ The outer size is the panel’s own resolution and 466 by 678 points at 3x. The inner size is not the panel’s resolution; the spec sheet says 1878 by 2670, and 2007 by 2853 is 669 by 951 points at 3x, which is my inference about the rendered size, on an assumed 3x scale, until the simulator reports it. The developer post works through what that means, with the Plus-iPhone precedent (App Store Connect still asks for 1242 by 2208 screenshots from phones whose panels were 1080 by 1920) and, if the display does render at that size, the consequence that a point measures the same on both displays, about 153 to the inch.³ If you built anything on 626 by 890, including the 16:9 letterbox arithmetic, redo it with 669 by 951.

The app preview row. The same update added iPhone Duo to the app preview specifications, and there Apple’s own label is the interesting part: under “Device resolutions” the row lists 2034 by 1398 pixels and 2853 by 2007 pixels, so Apple calls 2853 by 2007 a resolution of the device, not a screenshot convention. The row’s “(19.5:9 aspect ratio)” label reads as the iPhone template’s and fits neither number; 2853 by 2007 is 1.42. Accepted preview resolutions are 886 by 1920 and 1920 by 886. The same page also makes the Plus precedent explicit: its 5.5-inch row separates “Rendered pixels” from “Physical pixels,” 2208 by 1242 against 1920 by 1080, which is the arrangement the inner display’s numbers imply. And the row carries a note that matters for anyone building a pipeline today: “Support for uploading assets for this device in App Store Connect will be available later this year.”¹⁷¹⁸

What has not appeared. The Get Ready for iPhone Duo page is unchanged since 4:10 p.m. PT on September 9: the Xcode 27.1 beta, the “Preparing your app for iPhone Duo” guide, and the in-person workshops still read “Coming later this month.”⁴ There are no iOS 27.1 or Xcode 27.1 release notes, and no documentation page for the reserved-region or arrangement APIs the talks describe; the SwiftUI, UIKit, and technology-overview indexes contain no iPhone Duo entry.⁴

Mock-ups: the fold, rendered by strangers

The most-starred thing anyone built in the first day is a browser. chuspeeism/iphone-duo is a Three.js fold animation “with projected screen UI, progressive blur, and custom image uploads,” MIT-licensed, created at 12:51 a.m. PT on September 10 and at 40 stars by mid-morning, with a live demo.⁵ It follows jal-co/iphone-duo, a React 19 component created during the event day itself whose readme opens “A composable React folding-phone study with drag-to-fold interaction, layered screen content, and progressive blur” and states that “The 3D phone model and desert wallpapers are by Apple.”⁶ That credit is the thing to notice: the model comes from Apple’s product page, and I found no Apple redistribution or commercial-use permission in either repository. Both say the Apple assets sit outside their MIT grant; chuspeeism keeps the model out of its repository and downloads it from Apple at build time, while jal-co ships converted model files in its own tree. Apple’s marketing guidelines settle the question of where they can go: a 3D rendering or simulation of an Apple product is on the list of uses not permitted in marketing materials, so these studies are for internal demos, prototypes, and study, and Apple’s own bezels are the asset for anything customer-facing.²

One derivative and one independent tool take the idea further. bonxn/dood-iphone-duo adds screen videos and an MP4 export of the fold transition; huanglizhuo/iPhoneDuoMock, “Duo Studio,” is an independent browser workbench, in Chinese, that takes outer and inner screenshots, poses them on Apple’s model, and exports PNG, MP4, WebM, GIF, and, in its own words, strict-size interface PNGs for store listings.⁷ Its readme says its four store-listing sizes come from Apple’s specification as read on September 10 and that pixel size does not equal runtime logical point size, which is the right caveat; App Store Connect will not accept Duo uploads until later this year anyway.⁷¹⁷

A third study takes the opposite approach: bravohenry/iphone-duo-motion-study, at 6 stars, replays Apple’s own product-page viewer in WebGL from the model files Apple delivers, with an exploded device-anatomy view, and ships no license file at all.⁵

And there is the genre nobody planned: MacBook lid animations. lqSky7’s macTilt drives a copy of the Duo’s fold blur from the MacBook’s lid-angle sensor, in native Swift, so the whole macOS display frosts and slides to black as the lid closes.⁵ It is the one project from the day that made me laugh, and its readme has the cleanest one-line read of Apple’s transition I have seen: “When the lid closes, the picture on its screen stays where it is in space while the hardware sweeps through it: the image frosts over and slips into black without ever changing its size.”⁵

Frame from Apple’s September 9, 2026 event stream, 11:11 a.m. PT. The fold-animation clones copy the transition this device made famous in one keynote.

Code: sketches until the SDK ships

openHacking/DuoKit is the one runnable example set: 12 SwiftUI examples, MIT-licensed, from adaptive layout, split views, and grids through safe areas, fold avoidance, reserved regions, adaptive toolbars and tab views, presentations, Split View multitasking, multiple displays and scenes, and a complete sample app.⁸ Its readme is honest about the ground it stands on: “This first release builds with Xcode 26.6 and iOS 26.5. Examples 05, 06, and 11 use a clearly labeled simulator for iPhone Duo concepts that require the iOS 27.1 SDK. They do not claim to reproduce hardware behavior.”⁸ Read it as a study guide to the talks with code you can run against the layout rules that already exist on iOS 26, and not as a test of anything Duo-specific. yunodevs/DuoLayoutKit is a smaller Swift package with the same caveat, offering to “turn folded and unfolded poses into plain layout intent.”⁹

The limit on all of it is the one the developer post states: the reserved-region API, the arrangement views, the toolbar axis behavior, and the camera accessory exist today as narration and on-page code snippets in four Tech Talks, not in any SDK header or documentation page. No SDK has them, so no repository compiles them, and every API name in every repository, including the ones on this site, is copied from a pre-release talk page. The first thing to do when the Xcode 27.1 beta lands is diff the names against the headers.

Agent skills: the new day-one artifact

The surprising output of the first 24 hours is instruction sets for coding agents, which arrived alongside, and mostly ahead of, the first example code. Seven repositories describe themselves as skills or briefs for adapting apps to iPhone Duo, and one of them landed in an established collection: FloWritesCode/fwc-swiftui-skills, a 154-star set of SwiftUI skills, added swiftui-iphone-duo at 11:34 p.m. PT on September 9 with the commit message “Add a SwiftUI iPhone Duo skill for adaptive foldable layouts.”¹⁰ mirzaaghazadeh/iphone-duo-skills, at 12 stars, installs nine skills with a single command and says it distills “what exists into structured guidance an agent can act on, plus reference sheets for device facts and the full API surface.”¹⁰ mahdi-salmanzade/iphone-duo-skill aims at migration, with workflows for SwiftUI, UIKit, React Native, Expo, and Flutter.¹⁰

The most careful of them is the one that says the least. bahimzabir/iphone-duo-adaptive-ui opens with a warning: “This skill was assembled on 2026-09-10, one day after Apple published the iPhone Duo Human Interface Guidelines page and six Tech Talks, and before the tooling and reference documentation were available.”¹⁰ That sentence should be at the top of every one of these, because a skill is a claim about an API surface, and the surface is not published. A “full API surface” reference sheet, one day in, is a copy of talk-page code and narration with the same failure modes as mine. The useful reading of this wave is different: this launch produced agent instructions in the same hours as its first sample code, and the people writing them are treating Apple’s talks as the spec. When the SDK ships, the skills that survive will be the ones that cite timestamps and get re-checked against the headers.

Watch on YouTube ↗

Flo writes Code walked through the same material on video at 6:05 a.m. PT on September 10, the morning after his skill landed.¹⁵

The three questions developers are asking

The indie developers who think in public did so on Mastodon within hours, and three questions recur.¹¹

Where is the simulator? Greg Pierce found no iPhone Duo in the Xcode 27 RC’s Device Hub list at 12:12 p.m. PT and guessed it would come with 27.1. Craig Hockenberry at 12:27 p.m.: “It looks like Xcode 27.1 is needed to test the iPhone Duo resizability - and that hasn’t been uploaded yet.”¹¹ Paul Solt’s video that evening carries the answer in its title, “iPhone Duo Isn’t in Xcode 27 Yet.”¹⁵ Apple’s answer is the developer page’s “Coming later this month,” and the first Tech Talk’s description of the simulator’s open, close, rotate, and fold controls is the only preview.⁴ Pierce’s earlier hope, the day before the event, was “that there is nothing about the iPhone fold software that requires developers to have hardware to adequately test their apps”; the talks answer that one with a simulator, on a date Apple has not given.¹¹

What does an un-adapted app look like? Hockenberry, at 11:55 a.m. PT: “One thing that Apple didn’t show: an iPhone app that had not been adapted for the Duo’s display.”¹¹ The partial answer is in the first Tech Talk, which the developer post quotes: an app built without the iOS 27 SDK runs at “a familiar size and aspect ratio” when the device is open, the iOS 27 SDK extends it to the left of the status bar, and only the iOS 27.1 SDK reaches the edge. 9to5Mac’s Zac Hall organized the same three tiers on September 10 under the heading “Three levels of iPhone Duo app support,” and made the point that some apps “require a lot more work than just building against the iOS 27.1 SDK.”¹³ Apple’s first Tech Talk shows the three states, and 9to5Mac published a look at how Duo treats apps not built for it on September 9; what nobody outside Apple can do until the simulator ships is run their own app through them.

How does state survive the fold? Steve Troughton-Smith, at 9:37 a.m. PT on September 10: “If you’re using a UISplitViewController with a Compact view controller set, iPhone Duo raises some pretty ominous questions about state restoration when switching from folded to unfolded. Many of Apple’s own examples keep UI elements in the same physical location as the screen opens up, part of the magic of the illusion of the animated folding transition, which would be hard enough with a single horizontally-resizing app window, never mind a duplicate compact/regular hierarchy.”¹¹ The guidelines have one sentence on it, “Keep functionality and the state of elements the same between displays,” and the talks describe the split view collapsing and expanding, but neither says how a compact hierarchy and a regular one hand a selection back and forth mid-animation.¹⁶ That is the open question of the launch, and James Thomson’s reaction stands for a lot of people: “It looks like the Duo is going to require a lot of rethinking how my UI works.”¹¹

Two more reactions frame the mood. Troughton-Smith, at 12:16 p.m. on September 9, linking the first Tech Talk: “This is like a whole new platform dropping with a month’s lead time.”¹¹ And Pierce, on whether to ship day one: “If you choose to bust your butt to ship Duo support on Day 1 you are doing that for yourself.”¹¹ Jordan Morgan’s digest of the six talks, posted that afternoon, notes that “Some new iOS 27.1 API reference pages weren’t available at writing,” and that he had an AI read the sessions before he finished them; so did I, and the design post is what came of checking every line of it against the subtitle tracks.¹² The Hacker News thread on Apple’s product page, for scale, stood at 1,346 points and 2,343 comments by mid-morning; in the comments I sampled, the crease and the price led, with layout and developer subthreads underneath.¹⁴

What I would use today, and what I would wait for

• Use: Apple’s bezel pack, for mock-ups and marketing images of your own app; App Store Connect’s sizes, for any screenshot pipeline you are building now, knowing Duo uploads open later this year; DuoKit, as a guided reading of the talks with code that runs on iOS 26.
• Use with care: the fold studies for an internal demo or a prototype only, since Apple’s guidelines list 3D renderings and simulations of its products among the uses not permitted in marketing materials; any agent skill, as a checklist to argue with rather than a source of API names.
• Wait: for the Xcode 27.1 beta before writing a line against ArrangementView, reserved regions, or the toolbar axis APIs; for the “Preparing your app for iPhone Duo” guide before deciding a migration plan; for a dedicated iPhone Duo Figma file before treating any Figma frame as final; the iOS 27 UI Kit for Figma and the PNG bezels are enough to start layout work today.

Key Takeaways

For designers:

• Apple’s iPhone Duo bezels exist, in Photoshop and PNG, two finishes, five poses; the inner screen cutout is 2853 by 2007, App Store Connect’s size, not the panel’s; they are the asset Apple’s guidelines name for marketing, and 3D renderings are not permitted there.¹²
• App Store Connect’s screenshot row is the first point-size evidence: 669 by 951 on the inner display and 466 by 678 on the outer, at an assumed 3x; the rendering mechanism is an inference until the simulator ships.³

For developers:

• Nothing built in the first day compiles against a Duo API; Apple still lists the SDK as coming later this month, and every API name in the wild is copied from pre-release talk pages; diff them against the headers.⁴⁸¹⁰
• The open question is state across the fold for compact-and-regular hierarchies; Apple’s guidance so far is one sentence.¹¹¹⁶

For anyone watching the agent economy:

• Seven instruction-pack repositories for coding agents appeared in the first 24 hours, alongside the first example code, one of them inside a 154-star collection; the good ones carry a date and a warning.¹⁰

FAQ

Did Apple release a Figma or Sketch kit for iPhone Duo?

No. As of the morning of September 10, the Design Resources page lists iPhone Duo product bezels for Photoshop and PNG only. The iOS 27 and iPadOS 27 UI Kit is available for Figma and Sketch, but the page does not list a Duo file.¹

What screenshot sizes does App Store Connect want for iPhone Duo?

1398 by 2034 pixels for the outer display and 2007 by 2853 pixels for the inner display, each in both orientations, added September 9 per App Store Connect’s release notes; app previews are 886 by 1920 or 1920 by 886, and uploads for iPhone Duo open later this year.³¹⁷¹⁸

Can I build against the iPhone Duo APIs today?

No. The Xcode 27.1 beta that carries the iOS 27.1 SDK is listed as coming later this month, and no documentation pages exist for the reserved-region or arrangement APIs. The community repositories that name those APIs took the names from the Tech Talks’ narration and on-page code.⁴⁸¹⁰

Is there an iPhone Duo simulator?

Not in the Xcode 27 release candidate. The first Tech Talk describes an iPhone Duo simulator with open, close, rotate, and fold controls in Xcode 27.1.⁴¹¹

Sources