Summary of Notable Changes in iOS App Development (2026/10/07): App submissions for iPhone Duo now open, changes to UIView layout margins, and more
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When developing iOS apps, it's important to keep an eye not only on Apple's beta releases but also on specification changes to SDKs and tools in use, from a maintenance perspective. This time, since multiple developments overlapped — including the start of app submission acceptance for iPhone Duo, Xcode 27.1 RC, and iOS 27.2 Beta 3 — I decided to summarize the topics that caught my attention.
Apple
App Submission Acceptance Begins for iPhone Duo
In preparation for the October 23, 2026 launch, Apple Developer News published a preparation and submission guide (dated October 5, 2026). At the time of writing this article, it was only available in English and no Japanese version could be found. The main points of the guide are as follows.
- Recompile with Xcode 27.1 and verify behavior for each pose and orientation in Device Hub
- Screenshot and App Preview specifications for iPhone Duo have been published, and a product page preview tool has been added to App Store Connect
- App submissions optimized for iPhone Duo are now being accepted
Apps and games submitted after April 2027 will be required to include screenshots for iPhone Duo. Apple has stated "any apps or games" as the target, which can be read as applying regardless of whether the app is optimized for iPhone Duo.
Also in April, the minimum required version of Xcode needed to build apps uploaded to App Store Connect is raised each year as usual. Most recently, Xcode 26 or later became required starting April 28, 2026 (Upcoming Requirements). The requirements for April 2027 have not yet been announced, but following the usual pattern, it is assumed that Xcode 27 or later will be required.
According to the iOS & iPadOS 27 Release Notes, building with the iOS 27 SDK enables window resizing for iPhone apps running on iPad and iPhone Mirroring as well. As a result, even apps that do not support iPhone Duo will inevitably need to adopt layouts that adapt to changes in window size.
Xcode 27.1 RC Released
The build number increased from Beta 1's 27A9269 to 27A9275, but the release notes content is the same as Beta 1, with no changes listed. Issues such as compile errors in Mac Catalyst when using APIs specific to iOS 27.1, StandBy not being available in iPhone Duo Simulator, and the limitation where most App Extensions cannot be run or debugged remain in Known Issues.
Xcode 27.2 Beta 2 Released
The main changes from Beta 1 are as follows.
- A
GetCodeCoverageMCP tool has been added to Coding Assistant, which retrieves code coverage from recent test results - A "Display" group has been added to the canvas override picker in Previews (this was already included in Xcode 27.1 Beta 1)
- Fixed issues in Device Hub where input could not be entered into older OS simulators such as iOS 17, and where input would stop reaching physical devices after a period of inactivity
- Fixed an issue where Previews would fail with CRLF line ending files, and an issue where deleted simulator runtimes would reappear after restarting
The note in Beta 1 stating "SDK and simulator for iPhone Duo will be provided in a future Xcode 27.1" has been changed to a message directing users to obtain Xcode 27.1 beta from the download page. Known Issues related to iPhone Duo have also been added. Meanwhile, the crash during code completion on macOS 27.2 beta has been removed from Known Issues.
iOS & iPadOS 27.2 Beta 3 Released
The release notes for Beta 2 were unchanged from Beta 1, and Beta 3 primarily added the following.
- Starting with iOS 27.1, the default layout margins of
UIViewhave become zero. To inheritsystemMinimumLayoutMarginsprovided to a view controller's root view in subviews,preservesSuperviewLayoutMarginsmust be set totrue - The API for the EU-targeted ATT expanded prompt, added in Beta 1, was renamed twice (
requestTrackingAuthorization(usingExpandedInterface:...)→requestTrackingAuthorization(preferExpandedInterface:...)→requestTrackingAuthorizationPreferringExpandedInterface:)
iOS 26.7.1 Security Update
iOS 26.7.1 and iPadOS 26.7.1 were released on September 28, 2026. This fixes a CoreGraphics vulnerability (CVE-2026-86950) where processing a malicious file could allow arbitrary code execution. Apple has stated that it is aware of reports that this may have been exploited in extremely sophisticated attacks targeting specific individuals on versions prior to iOS 27.
Firebase
App Crash on Launch with Firebase Analytics (Server-Side Outage)
On September 29, 2026 (UTC), an outage occurred where apps incorporating Firebase Analytics would crash at launch with key cannot be nil (GitHub issue). According to the official blog, an old configuration flag was deleted on the server side while a reference to that flag remained in the SDK, causing a fatal error upon retrieval. The issue was fixed on the server side approximately two hours later.
Crash reports continued after the fix, but this was explained as a delay caused by crash reports being sent on the next app launch. As a preventive measure, the official blog states that an SDK patch to validate received payloads is planned for release.
Summary
Submission acceptance has begun, and there are now about two weeks until the iPhone Duo launch. However, since what I have available is Xcode 27.1 RC, I'm torn between waiting for the official release before submitting. There are still about six months until screenshots become mandatory, but even for apps that don't plan to support Duo, it would be wise to prepare early.
Another thing that caught my attention was the layout margins change revealed in iOS 27.2 Beta 3. Since the target is "iOS 27.1 and later," once iOS 27.2 is distributed, behavior is expected to change on existing iPhones other than iPhone Duo as well. It's listed as a New Feature, but screens that use Auto Layout with margins as a premise may have their appearance break, so I'd like to verify this once in the 27.2 beta.
Since information surrounding iOS app development changes rapidly, I plan to write another article the next time notable changes accumulate.
Job Listing: Classmethod is Hiring iOS Engineers
The Starbucks Digital Technology Division is looking for engineers who can develop iOS apps. We are waiting for applications from people who would like to join us and share knowledge about new Xcode and iOS features together in the misc-ios channel!
We are also hiring iOS/Android engineers in other areas. Let's talk about mobile app development together!