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Checklist: iPhone Duo & Adaptive Layout Review ​

Review gate for any iOS UI change once the app targets iPhone Duo. It applies to both SwiftUI and UIKit. Tag findings Critical/High/Medium/Low/Nit, and block on Critical/High. Source of truth: HIG — Designing for iPhone Duo and Preparing your app for iPhone Duo. How-to: skills/ui/ios/iphone_duo_adaptive_layout.md.

Build (Critical) ​

  • [ ] Built with Xcode 27.1 or later. Xcode 26 builds don't extend under the status bar and camera.

Resizing (Critical/High) ​

  • [ ] No layout decision reads userInterfaceIdiom, UIInterfaceOrientation, the device model, or UIScreen bounds.
  • [ ] Layout is driven by size classes and the container's or scene's bounds, with no fixed widths or heights sized to a specific iPhone.
  • [ ] Content respects layout margins and safe-area insets, including the asymmetric leading or trailing inset a vertical bar adds.
  • [ ] Screen renders correctly on the outer display, inner portrait, inner landscape, partially folded, and inner-display Split View.
  • [ ] Opening, closing, and folding keep state: scroll position, selection, drafts, navigation path, and playback.
  • [ ] Every control and piece of content is reachable in every pose. Overflowed items are still reachable through the overflow menu.

Reserved Regions (High) ​

  • [ ] No interactive control, text, or essential content sits under an active fold (.division) or a camera (.occlusion).
  • [ ] Custom layouts query reservedRegions(kind:…) rather than hard-coding hinge or camera coordinates.
  • [ ] Grids use an even column count when divided by the fold.
  • [ ] Right-to-left layout verified. Reserved-region mirroring (layoutDirectionBehavior) is used correctly.
  • [ ] Fold transitions make small adjustments, with no dramatic rearrangement.

Bars & Toolbars (High/Medium) ​

  • [ ] Bars come from navigation containers (.toolbar in NavigationStack/NavigationSplitView, or navigationItem in UIKit). There are no custom UIToolbar/UITabBar/UINavigationBar bars.
  • [ ] Every non-text toolbar item has both a title and a symbol. No item that must appear vertically uses a custom view or is text-only.
  • [ ] Order: Back/Close first, then prominent actions (Done pinned via .topBarPinnedTrailing / pinnedTrailingGroup).
  • [ ] Related items grouped with ToolbarItemGroup / UIBarButtonItemGroup, with no manual spacers.
  • [ ] Visibility priorities set: frequent and badged items .high, rare items .low.
  • [ ] Custom overflow menus moved into ToolbarOverflowMenu / additionalOverflowItems. The ellipsis symbol is used only for overflow.
  • [ ] Compression behavior fits the screen: the tab bar is kept for navigation-focused screens, and toolbar items are kept (prefersToolbarItems / prefersBarItems) for task-focused screens.
  • [ ] Any .horizontalOnly axis behavior is intentional. The item is hidden when there's no horizontal bar.
  • [ ] Controls for a non-trailing pane stay with that pane.
  • [ ] Vertical bars are disabled only for full-screen, non-scrolling UI, as a stable choice that isn't toggled by view state.

Containers & Presentation (Medium) ​

  • [ ] System containers (split views, tab views, navigation stacks, arrangement views) are preferred over custom containers.
  • [ ] Arrangement views aren't nested in a List, ScrollView, or split-view column, and navigation wraps them.
  • [ ] Sheet placement (presentationPlacement / preferredPlacement) chosen deliberately on the inner display.
  • [ ] Hero and background images extend under the vertical bar (backgroundExtensionEffect / UIBackgroundExtensionView).

Camera (High, if the app captures media) ​

  • [ ] The capture device is selected by facing direction and re-evaluated when the app changes display.
  • [ ] Preview and orientation stay correct after opening or closing mid-capture.

Accessibility & Tests ​

  • [ ] Largest Dynamic Type size verified on the outer display (shortest height) with vertical bars.
  • [ ] VoiceOver order stays logical when bars move to the side and panes split at the fold.
  • [ ] UI tests locate elements by accessibility identifier, never by coordinates, because positions change per pose.
  • [ ] Previews or snapshots cover compact (outer) and regular (inner) size classes.

Verdict ​

  • [ ] Verdict recorded: Approve / Approve-with-nits / Request-changes.
  • [ ] Every Critical/High finding has a file:line reference, the pose where it reproduces, and a concrete fix.