Liquid Glass

Liquid Glass

Overview

Use this skill to bring a macOS SwiftUI app into the modern macOS design system with the least custom chrome possible. Start with standard app structure, toolbars, search placement, sheets, and controls, then add custom Liquid Glass only where the app needs a distinctive surface.

Prefer system-provided glass and adaptive materials over bespoke blur, opaque backgrounds, or custom toolbar/sidebar skins. Audit existing UI for extra fills, scrims, and clipping before adding more effects.

Workflow

1. Read the relevant scene or root view and identify the structural pattern: NavigationSplitView, TabView, sheet presentation, detail/inspector layout, toolbar, or custom floating controls.
2. Remove custom backgrounds or darkening layers behind system sheets, sidebars, and toolbars unless the product explicitly needs them. These can obscure Liquid Glass and interfere with the automatic scroll-edge effect.
3. Update standard SwiftUI structure and controls first.
4. Add custom glassEffect surfaces only for app-specific UI that standard controls do not cover.
5. Validate that glass grouping, transitions, icon treatment, and foreground activation are visually coherent and still usable with pointer and keyboard.
6. If the UI change also affects launch behavior for a SwiftPM GUI app, use build-run-debug so the app runs as a foreground .app bundle rather than as a raw executable.

App Structure

• Prefer NavigationSplitView for hierarchy-driven macOS layouts. Let the sidebar use the system Liquid Glass material instead of painting over it.
• For hero artwork or large media adjacent to a floating sidebar, use backgroundExtensionEffect so the visual can extend beyond the safe area without clipping the subject.
• Keep inspectors visually associated with the current selection and avoid giving them a heavier custom background than the content they inspect.
• If the app uses tabs, keep TabView for persistent top-level sections and preserve each tab's local navigation state.
• Do not force iPhone-only tab bar minimize/accessory behavior onto a Mac app. On macOS, prefer a conventional top toolbar and native tab/search placement.
• If a sheet already uses presentationBackground purely to imitate frosted material, consider removing it and letting the system's new material render.
• For sheet transitions that should visually originate from a toolbar button, make the presenting item the source of a navigation zoom transition and mark the sheet content as the destination.

Toolbars

• Assume toolbar items are rendered on a floating Liquid Glass surface and are grouped automatically.
• Use ToolbarSpacer to communicate grouping:
  • fixed spacing to split related actions into a distinct group,
  • flexible spacing to push a leading action away from a trailing group.
• Use sharedBackgroundVisibility when an item should stand alone without the shared glass background, for example a profile/avatar item.
• Add badge to toolbar item content for notification or status indicators.
• Expect monochrome icon rendering in more toolbar contexts. Use tint only to convey semantic meaning such as a primary action or alert state, not as pure decoration.
• If content underneath a toolbar has extra darkening, blur, or custom background layers, remove them before judging the new automatic scroll-edge effect.
• For dense windows with many floating elements, tune the content's scroll-edge treatment with scrollEdgeEffectStyle instead of building a custom bar background.

Search

• For a search field that applies across a whole split-view hierarchy, attach searchable to the NavigationSplitView, not to just one column.
• When search is secondary and a compact affordance is better, use searchToolbarBehavior instead of hand-rolling a toolbar button and a separate field.
• For a dedicated search page in a multi-tab app, assign the search role to one tab and place searchable on the TabView.
• Make most of the app's content discoverable from search when the field lives in the top-trailing toolbar location.
• On iPad and Mac, expect the dedicated search tab to show a centered field above browsing suggestions rather than a bottom search bar.

Controls

• Prefer standard SwiftUI controls before creating custom glass components.
• Expect bordered buttons to default to a capsule shape at larger sizes. On macOS, mini/small/medium controls preserve a rounded-rectangle shape for denser layouts.
• Use buttonBorderShape when a button shape needs to be explicit.
• Use controlSize to preserve density in inspectors and popovers, and reserve extra-large sizing for truly prominent actions.
• Use the system glass and glass-prominent button styles for primary actions instead of recreating a translucent button background by hand.
• For sliders with discrete values, pass step to get automatic tick marks or provide specific ticks in a ticks closure.
• For sliders that should expand left and right around a baseline, set neutralValue.
• Use Label or standard control initializers for menu items so icons are consistently placed on the leading edge across platforms.
• For custom shapes that must align concentrically with a sheet, card, or window corner, use a concentric rectangle shape with the containerConcentric corner configuration instead of guessing a radius.