Does 24/7 Fitness work on iPhone Duo?

Not yet. 24/7 Fitness runs letterboxed on the inner display, with black borders around an iPhone-sized window. Its latest version is built with the iOS 26.5 SDK, which Apple shows letterboxed on the inner display.

Is 24/7 Fitness letterboxed on iPhone Duo?

Apps built with the iOS 26 SDK or earlier show black borders around an iPhone-sized window on the inner display; iOS 27 apps resize to fill most of it, and iOS 27.1 apps fill it completely. Current status: Letterboxed.

All apps

24/7 Fitness

Name: 24/7 Fitness
Author: 24/7 Fitness

24/7 FitnessUtilities

View in the App Store

On iPhone Duo

Letterboxed

24/7 Fitness runs in an iPhone-sized window with black bars.

Its latest version is built with the iOS 26.5 SDK,[1] which Apple shows letterboxed on the inner display.[2]

How we know: From the app’s build
Checked on: Version iOS App 版本 2.1.17
Build: iOS 26.5 SDK
Latest version: iOS App 版本 2.1.17, Oct 13, 2026
Status updated: Oct 24, 2026

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Version history

Version iOS App 版本 2.1.17Letterboxed
iOS 26.5 SDK
Checked Oct 24, 2026

Sources

App Store build, version iOS App 版本 2.1.17
Built with the iOS 26.5 SDK. Uses none of Apple’s iPhone Duo APIs.
Apple Developer: Prepare your app for iPhone Duo