Two weeks after the iPhone Duo went on sale, Apple says more than 100,000 apps on the App Store are built for it, with thousands more arriving daily. For owners, that decides how the foldable feels: an optimised app fills both screens, while an old one sits in the middle of the inner display with black bars on each side.
The figure comes with a caveat: Apple confirmed what the number covers: apps compiled against version 27.1 of the iOS developer kit or a newer one. Such apps span both screens and move their buttons into the strip along the side. Apps compiled with the base iOS 27 kit stretch across most of the inner screen but stay clear of that bar, and anything older than that runs in a narrow strip.
The announcement came with a batch of newly updated apps: Microsoft’s Word, Excel, PowerPoint and OneNote, Zoom, Etsy, Goodnotes, the Halide Mark III camera app, and the NBA and NHL apps. Netflix, Instagram, WhatsApp, YouTube, Prime Video and MLB were already optimised. On the device, an optimised app carries a “Made for iPhone Duo” badge in its App Store listing.
Susan Prescott, who leads Apple’s developer relations, said the company was “grateful for their creativity and innovation” and that developers had embraced the phone quickly. Apple says it has run more than 50 in-person workshops in 19 cities, which more than 2,000 developers attended, so they could test their apps on real hardware.
The gaps are still visible. MacRumors’ list of apps that have not been updated includes Microsoft Teams and Authenticator, Google Docs, Sheets, Slides and Home, PayPal, Venmo, Steam, DoorDash, Uber Eats, Starbucks, Nike, FedEx, UPS and YouTube Music. TechCrunch found that the Spotify update was not yet showing on its review unit, so some of Apple’s list may take time to reach everyone.
Developers who use standard SwiftUI and UIKit components get much of the adaptation for free, Apple says, and new APIs let them tune apps for the Duo’s different layouts and poses. Since iOS 27.2 the phone also works with the USB-C Apple Pencil, so drawing and note apps such as Procreate Pocket and Apple Notes can use it.
The phone itself is hard to get. Shipping estimates have slid into next year since Apple’s CEO said the Duo was sold out, and the company said on its earnings call that it is hard to predict when the supply limits will ease.
