iPhone Duo Adaptivity Audit

The inner display of iPhone Duo, iPhone Mirroring, iPhone apps on iPad and Split View all resize your app. Code that reads the main screen, the device orientation or the idiom gets wrong values there. This skill finds that code and replaces it with values from the view's own window and traits.

What it does

• Finds legacy screen code: UIScreen.main, screen bounds and scale, keyWindow and connectedScenes.first.
• Removes layout forks on orientation and idiom: replaces them with size classes and the container size.
• Plans the UIScene migration: the latest SDK requires the UIScene lifecycle, or the app does not launch.
• Checks UIRequiresFullScreen: from iOS 27, it no longer opts the app out of resizing.
• Fixes Face ID assumptions: iPhone Duo has Touch ID, so copy and symbols branch on LAContext.biometryType.

How it works

1. A read-only scanner (duo_scan.py) lists every match with a rule ID.
2. The skill reads each match and classifies it: replace, keep with a reason, or ask you.
3. If Xcode 27 has its UIKit modernization skill, this skill uses it for bulk UIKit rewrites.
4. You approve each change. The skill applies it, builds and scans again.

Works with

SwiftUI and UIKit apps in Xcode. The skill references include before-and-after code for each replacement.

Why use this skill

This is the base for all other iPhone Duo work. A layout that depends on the screen, the orientation or the idiom is wrong on iPhone Duo before any foldable-specific change.