iphone-duo-bars · diff
git:20260913.62bff5b to git:20260913.566635a
19 added, 7 removed. Audit A to A.
---
name: iphone-duo-bars
description: >-
Prepare navigation bars, toolbars and tab bars for iPhone Duo's vertical bars,
- where controls move to the side of the inner display in landscape. Use when a
+ where controls move to the side of the outer display and of the inner display
+ in landscape. Use when a
developer asks about vertical bars, bar item ordering, back or close button
placement, pinned trailing or prominent actions, toolbar items without titles,
axisBehavior, symbol-only items and badges, custom views in toolbars,
toolbarVerticalEdge or verticalBarEdge, overflow menus and ToolbarOverflowMenu,
visibilityPriority, toolbar or tab bar compression, custom UIToolbar or
UINavigationBar instances, or opting out with toolbarVerticalBehavior. Covers
SwiftUI and UIKit, based on Apple's "Raise the bar with iPhone Duo".
---
# iPhone Duo vertical bars
- On the inner display in landscape, iPhone Duo moves controls that normally sit at the
- top and bottom to the side, keeping vertical space for content and controls within
- reach. In portrait they return to a horizontal layout. (Tech Talk 111462, 0:28)
+ On the outer display and on the inner display in landscape, iPhone Duo moves controls
+ that normally sit at the top and bottom to the side, keeping vertical space for content
+ and controls within reach. Only the inner display in portrait keeps horizontal bars.
+ Top to bottom the side stack is Dynamic Island, status bar, toolbar (with navigation
+ buttons), tab bar. (Tech Talk 111462, 0:28; Tech Talk 111466, 5:07; HIG *Designing for
+ iPhone Duo* › Vertical controls)
Read `references/vertical-bars.md` for the code; `references/api-availability.md` for
which parts compile with the selected SDK — `axisBehavior`, `toolbarVerticalEdge`,
compression behavior and the opt-out need the **iOS 27.1 SDK**, while titles, symbols,
badges, placements, `visibilityPriority` and `ToolbarOverflowMenu` work today.
+ Where the corner camera and the side controls physically sit:
+ `references/device-geometry.md`.
## How the system decides
- **Only container bars participate.** SwiftUI: `.toolbar` inside `NavigationStack`
or `NavigationSplitView`. UIKit: `UINavigationController` and `UITabBarController`.
Standalone `UIToolbar`, `UINavigationBar`, `UITabBar` content is not considered.
(2:00)
- **One shared region.** Navigation, toolbar and tab bar controls stack into one
vertical region. In split views only the detail column participates; inspectors
get no bar of their own; sheets behave differently per display. The bar is aligned
with the hardware and stays on the same side in right-to-left languages. (3:09)
- **Fixed width, flexible height.** Items with an icon go vertical; text-only items
stay horizontal. The title is still required — it is used in overflow menus and
expanded forms. (5:56)
- **Custom views stay horizontal by default.** (8:00)
- **Overflow runs bottom to top**, and toolbars compress before the tab bar by
default. (11:40, 13:10)
## Audit checklist (per screen)
1. **Container.** Is every bar item owned by a navigation or tab container? Scanner
rule `DUO007` finds standalone bars; move their items into the container.
2. **Order.** Top of the vertical bar: primary navigation (back or close), then
prominent actions (done, save). Use `.cancellationAction` / leading item groups
with `leftItemsSupplementBackButton = false` for close, and
`.topBarPinnedTrailing` / `pinnedTrailingGroup` for prominent actions. Keep
- controls associated with the container they belong to. (4:29)
+ controls associated with the container they belong to. (4:29) Group related items
+ with `ToolbarItemGroup` / `UIBarButtonItemGroup` instead of manual spacing, and keep
+ controls next to the content they affect — Mail's list controls stay above the
+ leading pane. (HIG › Vertical controls)
3. **Title and symbol on every item.** Provide both, even when only the symbol shows.
4. **Text that carries information stays horizontal.** A symbol plus redundant text →
symbol only (use a badge for counts, iOS 26 badge API). Text with standalone value
(a cart showing a total) → keep, and it stays in the horizontal bar. (9:00)
5. **Axis for items that change shape.** An item that switches between symbol and
text (Select ↔ Done) → `.horizontalOnly`, and keep related items on the same axis.
A custom view that has a vertical representation → `.verticalPreferred`. (8:00)
6. **Custom views fit.** Fixed bar width, or a vertically adapted layout keyed off
`toolbarVerticalEdge` / `verticalBarEdge`. Flexible spacers collapse to zero
vertically; fixed spacers keep their minimum. Legible with no scroll edge effect
and with the Reduce Transparency background. (10:07)
7. **Overflow.** One overflow menu, and the ellipsis symbol belongs to it (scanner rule
`DUO011`). A custom ellipsis menu is one of two things: a grab bag of secondary
actions — move it into `ToolbarOverflowMenu` / `additionalOverflowItems` so people
see one "more" instead of two — or a single named function such as Filter, which
deserves its own symbol and title so it can survive in the vertical bar. (11:40)
8. **Compression.** Navigation-focused apps: default (toolbar compresses first).
Task-oriented screens where actions matter more than tabs:
`.toolbarVerticalCompressionBehavior(.prefersToolbarItems)` /
`verticalBarCompressionBehavior = .prefersBarItems`. (12:23)
9. **Priority.** Set `visibilityPriority` on groups first, then items. Compose / New
Note / primary creation: high. Status-bearing items (badged inbox): high, to
preserve glanceability. Rare actions: low. (13:10)
10. **Opt-out only where it fits.** Single-page, bottom-heavy layouts (Calculator-like)
and sheets with a single close button. Not as a fix for items that overflow. (14:21)
+ Otherwise don't override the default placement; a full-width layout suits only
+ immersive, non-scrolling screens that don't conflict with the Dynamic Island or
+ status bar. (HIG › Vertical controls; Tech Talk 111466, 6:33)
## Output
One recommendation per screen (not per item) in the format of
`references/recommendation-format.md`, listing the checklist steps that apply. Items
that need 27.1 APIs are marked *blocked* when the SDK lacks them; everything else can
ship now and improves bars on every iPhone.
## Verify
- Pose matrix P2 (outer display landscape, keyboard up), P3 (inner landscape: vertical
- bar), P4 (inner portrait: horizontal), P11 (right-to-left), P12 (Reduce Transparency)
+ Pose matrix P1 (outer display: side controls), P2 (outer display landscape, keyboard
+ up), P3 (inner landscape: vertical bar), P4 (inner portrait: horizontal), P11 (right-to-left), P12 (Reduce Transparency)
from `references/pose-test-matrix.md`. Check which items overflow and in what order.