Apple’s newly unveiled iPhone Duo may face the same app compatibility problem the company used to criticise Android foldables for. Documentation for iOS 27.1 indicates that apps not updated for the new form factor could appear in a portrait-shaped window surrounded by black bars.
During the launch presentation, Apple chief executive John Ternus argued that rival foldable phones could feel like “two phones awkwardly stuck together”. He said their square inner screens made vertical content less effective, while films were surrounded by large black bars.
However, Apple’s own guidance for developers suggests that older apps will also be letterboxed on the iPhone Duo’s larger internal display. Applications that have not been updated for iOS 27 will be shown with black space at either side rather than expanding across the full screen.
Apps that support iOS 27 but are not ready for iOS 27.1 will reportedly face a further limitation, with the application unable to use the area beside the device’s sidebar. That could leave parts of the display unused even when an app has received an update.
Why foldable phone apps remain a challenge
App scaling was a notable weakness of early Android foldables, when many services had been designed around the proportions of a conventional smartphone. Developers and Google have since improved support for larger and changing screen layouts as foldable devices have become more established.
Android has also gained tablet-style interfaces for some major services, including Instagram. The progress means Apple is likely to benefit from an established developer ecosystem when it introduces its own foldable design, but its first-generation hardware will not automatically eliminate compatibility problems.
Developers will need to adapt their software for the iPhone Duo’s display, sidebar and changing orientations. Until that happens, Apple’s foldable phone may reproduce the same black-bar effect highlighted in its presentation as a shortcoming of rival devices.
