In order for an app to be optimized for the iPhone Duo, the developer needs to build it with the iOS 27.1 SDK or later. Apps optimized for the iPhone Duo fill the entire inner display, and the app's toolbar appears vertically below the status bar.
Apps built with the iOS 27 SDK fill most of the inner display on the iPhone Duo, but they still avoid the status bar on the right edge.
Apps built with the iOS 26 SDK or earlier run on the iPhone Duo, but the app will appear in the center of the inner display with lots of empty space on each side.
Many more apps are being optimized for the iPhone Duo each and every day, so keep a close eye on the App Store's updates menu.
Some Apple retail employees have been told to warn customers against visiting to purchase an iPhone Duo without a pre-order on Friday, October 23.
Apple Store employees told MacRumors that they have been advised that there will likely be no iPhone Duo stock available for walk-in purchases on launch day. Staff have been instructed to discourage customers without pre-orders from coming in...
Tuesday October 20, 2026 11:12 am PDT by Juli Clover
With just three days to go until the iPhone Duo is released, Apple is getting ready for the launch. Behind the scenes, the App Store now has screenshots of Apple's built-in apps running on the Duo. We've seen some apps in marketing materials, but images of the ones we haven't seen give us an idea of what it will be like using the iPhone Duo day to day.
Many apps are shown in landscape...
Sunday October 18, 2026 7:33 am PDT by Joe Rossignol
Despite knowing that the iPhone Duo would face "severe supply constraints" due to manufacturing challenges, Apple chose to begin iPhone Duo pre-orders on Friday instead of waiting until it had more inventory ready, according to Bloomberg's Mark Gurman. In his Power On newsletter today, he called this decision a "major mistake."
"Let me cut to the chase: Apple made a major mistake here," he...
Back in 2010, it's understandable the apps are not yet optimized for a new form factor (iPad) but in 2026, most apps used by users should have been optimized for the new form factor (iPhone Duo) considering a physically larger screen has been in existence since 2010.
There's a bit more to it than that. The sidebar, rounded edge, scaling up to "tablet mode" and down to "phone mode". How much content is visible on the front vs inner. Some apps, trivial. Other apps, especially those that don't use some of Apple's frameworks directly, a bit harder. Heck, even just the UX may change enough with many apps to not be trivial. Then testing with physical hardware instead of simulators, etc. It'll get there, but just because the iPad exists doesn't mean it's easy to have an app that can shift its size elegantly for free.
Apple's first foldable iPhone, with a book-style design featuring a 5.4-inch outer display and a 7.6-inch inner display with a minimal crease down the middle.
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