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 a sense of anxiety about "how soon we need to support it."
Since the screen layout will be completely different from anything before, there is a possibility that existing app layouts will break, and we find ourselves in a situation where we need to catch up on information as quickly as possible...
In this article, I will summarize what I 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 based on SDK version.
For apps built with the iOS 26 SDK, it appears that the existing layout will be maintained on the inner display, but with margins 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 side 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 side by side
Things built with SDK versions prior to iOS 27 seem usable 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 will be updating your app, April 2027 appears to be the upload deadline, meaning you will essentially need to complete support by then or you will no longer be able to upload your app.
When will the simulator be available?
When working toward iPhone Duo support and wanting to be ready before release, being unable to use the simulator means we can't even identify the necessary changes needed.
At the time of writing this article, Xcode 27 RC is the latest version, 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 reportedly scheduled to be released in late September 2026, so I think that will be the first opportunity to identify layout issues and other problems on the iPhone Duo.
Closing Thoughts
Building with the iOS 26 SDK should allow existing apps to continue working, but until the simulator is released, I don't think we can definitively say that layout issues and similar problems won't occur.
With things like Liquid Glass support, it seems like not using standard UI components will leave you constantly scrambling to keep up with future updates, so if you are using customized navigation or tab bars, my impression is that this is a good opportunity to consider migrating to standard components.