Two weeks ago I wrote about what the foldable iPhone does to your layouts, and ended on a vague note because Apple had only promised that the App Store would accept iPhone Duo screenshots before the end of the year. That turned out to mean a Monday: on 5 October Apple opened submissions for apps built for iPhone Duo, shipped the Xcode 27.1 release candidate the same day, and slipped in a second announcement about new marketing assets on the App Store that has nothing to do with folding and quite a lot to do with how your app looks in search. The phone itself reaches customers on 23 October, so this is the calm week before people start posting photos of your app on it.
Same app, three builds, three looks
The first article said that an app built with an older Xcode gets a frame around it. Apple's three-step preparation page is now more precise than that, and the answer depends on which SDK your last release was compiled with, which is a question worth asking your developer today if you do not know.
The diagram shows the open inner display three times. Built with the iOS 26 SDK or earlier, your app runs at a familiar phone size in the middle of the big screen with empty space all around it, which works, in the way a postage stamp works on a large envelope. Built with the iOS 27 SDK, it resizes to fill most of the display but still keeps clear of the status bar on the right edge. Built with the iOS 27.1 SDK, the one that comes with Xcode 27.1, it takes the whole display, and the toolbars and tab bars move to a vertical strip under the status bar. Apple asks you to check that last point before shipping, because a screen that was designed around a bar at the bottom does not always enjoy finding it on the side.
There is a nice touch for teams short on time: in Xcode you can ask the coding assistant to "get my app ready for iPhone Duo", and a built-in skill scans the project for the usual suspects (sizes read from the main screen, layouts decided by orientation, code that assumes a wide screen means iPad). Apple itself says the skill does not catch everything, which is refreshingly honest for a robot.
The measurements, since you asked
People are already searching for these, so here they are, straight from Apple's screenshot specifications. iPhone Duo has two entries, one per display. The outer display takes 1398 × 2034 pixels in portrait, or 2034 × 1398 in landscape. The inner display takes 2007 × 2853 pixels in portrait, or 2853 × 2007 in landscape. The usual rules apply: one to ten screenshots per size, in JPEG or PNG, with no transparency.
One detail deserves a second look. For every other iPhone size, the page says which larger size App Store Connect will scale down if you leave the slot empty, and that is how most apps get away with a single set. For iPhone Duo, the page lists no such fallback. I would not conclude too much from a missing line in a table, but I would plan on producing real iPhone Duo screenshots rather than hoping a tall iPhone one gets stretched into shape.
April 2027, with small print
The news post says that starting April 2027, submitted apps and games must include screenshots for iPhone Duo. The specifications page words it more narrowly: screenshots will be required for apps that use the iOS 27.1 SDK or later. The two sentences do not say quite the same thing, and Apple has not explained the difference, so the safe reading is the one that costs you a few screenshots: if you plan to submit anything after next April, have them ready.
While you are in there, App Review has published new guidance on screenshots under guideline 2.3.3, and it comes with an actual number. For each device, more than half of the screenshots must show the app in use, so out of three, at least two. Marketing slides are welcome in the remaining ones; a set made of a splash screen, a login page and a slogan in large type is the example Apple gives of what gets sent back.
A banner of your own, and a face in search
The second announcement is for everyone, foldable or not. On iOS 27 and iPadOS 27, a product page can now open with a header, an image or a video that sits at the very top, and your app can show a dedicated search result asset in the Search tab instead of the usual row of screenshots. Both are optional: without a search asset, your In-App Events, previews and screenshots appear as before.
The specifications are wide formats, 21:9 for the header and 3:2 for search, and videos run from 5 to 30 seconds and loop, muted in search. Apple's house rules are the interesting part: no prices or discounts, no website addresses, no awards you have not received, no logos of other platforms, and everything has to suit a 4+ age rating even if your app is rated higher. So the "50% off this week" banner you were already picturing will have to say it some other way.
App Store Connect also gained two tools that marketing teams will like more than developers will. A preview tool shows how your screenshots, headers and text will look on the product page and in search, on different devices and in Dark Mode, before you submit anything. And an Asset Library keeps every image and video in one place, and lets you send assets for approval on their own, without attaching them to a new app version, which means the Christmas campaign can be approved in November and switched on when you are ready. The Marketing role has access, so nobody needs to borrow the Account Holder's password, not that anyone ever did that.
So what would I actually do?
I would start by finding out which SDK the current release was built with, because that decides whether your app is a postage stamp on 23 October. Then I would rebuild with Xcode 27.1, walk through the app in the iPhone Duo simulator, and take the two sets of screenshots during that same pass, since the screens are already in front of you. The header and the search asset can wait for a quiet afternoon with whoever looks after your brand; they are optional, and a rushed banner is worse than none. And if the build is still on an older Xcode, the Xcode 26 upgrade article explains why these upgrades are better done early than the week of a deadline.
If you want help
Rebuilding with the current SDK, fixing what moves, and getting the store listing through review is what my App Store and Google Play compliance service covers.
Sources: Prepare and submit your apps for iPhone Duo, Showcase your apps with new assets on the App Store, Three steps to make your app shine on iPhone Duo, Screenshot specifications, Creative assets specifications, App Store asset best practices, Manage your App Store assets, App Review guideline 2.3.3, Screenshots, Apple developer releases.