By when do we need to support iPhone Duo?
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Introduction
Apple's first foldable iPhone, "iPhone Duo," will be released on October 23, 2026.
Ever since the announcement, there has been widespread anxiety about "how soon we need to support it."
Since the screen layout will be completely different from anything before, existing app layouts could break, making it a situation where we need to catch up on information as quickly as possible...
In this article, I will summarize what we have found out.
Will layouts break immediately?
A Tech Talk was published to coincide with the announcement of iPhone Duo.
In it, there is mention of iPhone Duo support depending on the SDK version.
For apps built with the iOS 26 SDK, it seems that on the inner display, the existing layout will be maintained while padding appears on the left and right sides.
The following is how display support varies by SDK version:
- Built with SDK prior to iOS 27: Works as-is, but cannot make full use of the screen
- Built with iOS 27 SDK: The display area extends to the left of the status bar on the inner display
- Built with iOS 27.1 SDK: Reaches the edge of the screen, and standard navigation bar/toolbar buttons are laid out vertically rather than horizontally
Things built with SDK versions prior to iOS 27 seem to work as-is, but judging from the layouts shown in the video, the UX for iPhone Duo users will likely be significantly degraded without proper support.
Support Deadline
From April 2027 onwards, only apps built with iOS 27 or later SDK will be uploadable.
So assuming you plan to update, the upload deadline appears to be April 2027, meaning you effectively need to complete support by then or you will be unable to upload your app.
When will the simulator be available?
When working on iPhone Duo support, if you want to be ready before the release date, you cannot even identify what changes are needed without access to a simulator.
At the time of writing this article, Xcode 27 RC is the latest, but the iPhone Duo simulator is not yet available.
According to the Tech Talk, the iPhone Duo simulator should become available starting with Xcode 27.1.
The beta version of Xcode 27.1 is expected to be released in late September 2026, so I think that is when we will first be able to check for layout issues and such on the iPhone Duo.
Closing Thoughts
Building with the iOS 26 SDK apparently allows existing apps to continue working, but until the simulator is released, we cannot definitively say that layout issues and similar problems won't occur.
Between Liquid Glass support and everything else, my personal feeling is that if you don't use standard UI components going forward, you'll end up being dragged around by future updates — so if you're using customized navigation bars or tab bars, this might be a good opportunity to consider migrating to standard components.