Add Xcode 26 support to hosted macOS runners

Description

Apple has announced a new App Store submission requirement that directly impacts iOS and iPadOS CI/CD pipelines.

Starting April 2026, all iOS and iPadOS applications submitted to App Store Connect must be built using the iOS 26 SDK or later, which is only available in Xcode 26 or later. Builds produced with older SDKs (e.g., iOS 18.5) will be rejected with errors such as ITMS-90725: SDK version issue.

GitLab's current hosted macOS runners only support:

  • macos-14-xcode-15
  • macos-15-xcode-16

There is currently no hosted runner image that supports Xcode 26.

Proposal

Add a new hosted macOS runner image that includes Xcode 26, for example:

  • macos-26-xcode-26
  • macos-15-xcode-26

Links to related issues and merge requests / references