Summary of Notable Changes in iOS App Development (2026/10/07)
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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 in the SDKs and tools you use, from a maintenance perspective. This time, since several developments coincided — 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 posted preparation and submission guidance (dated October 5, 2026). At the time of writing, only the English version was available and no Japanese article could be found.
- 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
- Submissions for apps 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 described the target as "any apps or games," 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 typically raised each year. Most recently, Xcode 26 or later became required starting April 28, 2026 (Upcoming Requirements). The April 2027 requirements have not yet been announced, but following the usual pattern, Xcode 27 or later is expected to become 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 need to adopt layouts that adapt to changes in window size.
Xcode 27.1 RC Released
The build number has been updated from Beta 1's 27A9269 to 27A9275, but the release notes content is the same as Beta 1, with no changes listed. Issues that remain in Known Issues include a compile error in Mac Catalyst when using APIs specific to iOS 27.1, and limitations where StandBy cannot be used in the iPhone Duo Simulator and most App Extensions cannot be run or debugged.
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 previously included in Xcode 27.1 Beta 1)
- Issues in Device Hub have been fixed, including the inability to input to older OS simulators such as iOS 17, and input not 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 a restart
The note in Beta 1 stating "iPhone Duo SDK and simulator will be provided in a future Xcode 27.1" has been changed to guidance directing users to obtain Xcode 27.1 beta from the download page. Known Issues related to iPhone Duo have also been added. A crash during code completion on macOS 27.2 beta has been removed from Known Issues.
iOS & iPadOS 27.2 Beta 3 Released
The Beta 2 release notes were unchanged from Beta 1, and the following was added in Beta 3.
- Starting with iOS 27.1, the default layout margins of
UIVieware now zero. To have subviews inherit thesystemMinimumLayoutMarginsprovided to the root view of a View Controller,preservesSuperviewLayoutMarginsmust be set totrue - The API for the EU-targeted ATT expanded prompt, added in Beta 1, has been 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 is a fix for 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 vulnerability may have been exploited in highly sophisticated attacks targeting specific individuals on versions prior to iOS 27.
Firebase
App Crashes at Launch with Firebase Analytics (Server-Side Outage)
On September 29, 2026 (UTC), apps incorporating Firebase Analytics crashed 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 when fetching it. 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 due to crash reports being sent on the next app launch. As a preventative measure, the official blog states that an SDK patch to validate received payloads is planned for release.
Summary
Submissions are now open, and there are about two weeks left until the iPhone Duo launch. However, since the available tool is Xcode 27.1 RC, it is a difficult decision whether to wait for the official release before submitting. There is about half a year before screenshots become mandatory, but even for apps not planning to support Duo, it would be good to prepare early.
Another thing that caught my attention was the layout margins change revealed in iOS 27.2 Beta 3. Since it applies to "iOS 27.1 and later," once iOS 27.2 is distributed, behavior is expected to change on existing iPhones other than the iPhone Duo as well. While it is treated as a New Feature, screens that rely on margins in Auto Layout may have their appearance break, so it would be worth verifying once on the 27.2 beta.
Job Listings: Classmethod is Hiring iOS Engineers
Classmethod is looking for engineers who can develop iOS apps. We look forward to applications from those who would like to work with us, sharing thoughts on new Xcode and iOS features in the misc-ios channel! Let's talk about mobile app development!