fusengine/design-ios

Design iOS/macOS — Mockup and Handoff, Not Code

When

After design-system tokens exist. This skill never writes SwiftUI — it produces a static HTML mockup at exact device/window dimensions plus a spec that swift-expert or an Apple-platform developer implements.

Input

• design-system.md — OKLCH palette, typography direction, motion personality.
• The screen/flow to mock up and the target platform: iPhone / iPad (iOS) or a resizable window (macOS).

Steps — iOS

1. Map tokens to iOS roles. Typography → Dynamic Type text styles, anchored at Body 17pt down to Caption 2 11pt (never fixed point sizes) — see references/dynamic-type.md. Colors → semantic color roles (never raw RGB/hex) — see references/semantic-colors.md.
2. Pick the device viewport(s) from references/viewports.md — mock up in exact points at the chosen scale factor.
3. Build the HTML mockup: a device-frame <div> at the exact viewport dimensions, viewport-fit=cover meta tag, env(safe-area-inset-*) for notch/Dynamic Island/home indicator spacing. See references/mockup.md.
4. Apply Liquid Glass where it fits — a floating layer of controls above regular content, not a content background. Two variants: regular (content-aware, the default for controls) and clear (more transparent — dim the content beneath it ~35% when clear sits over light content, so controls stay legible). Plus control morphing, concentricity between nested shapes, layered icon treatment. Source: developer.apple.com/design/human-interface-guidelines/materials (Liquid Glass, iOS 26). See references/liquid-glass.md — do not invent numeric corner-radius values; none are published.
5. Verify touch targets and contrast: 44×44pt minimum touch target (see references/touch-targets.md); 4.5:1 minimum contrast in Dark Mode for body text (WCAG AA, HIG-endorsed) — check both light and dark against references/semantic-colors.md roles, not a single-mode check.
6. Sidebar navigation ≤ 2 levels deep. If the flow needs a 3rd level, restructure (tabs, push navigation, or a secondary sidebar) rather than nesting a 3rd disclosure tier — deeper sidebars are a documented HIG anti-pattern for iPadOS/macOS sidebars. Source: developer.apple.com/design/human-interface-guidelines/layout.
7. Write the handoff spec per references/handoff-swiftui.md: named tokens only (never raw values), Dynamic Type text styles (never fixed sizes), semantic colors, explicit sizing behavior (fixed/hug/fill) per element, all interaction states (disabled/pressed/focused), spacing in pt.

Steps — macOS

1. Map tokens to macOS text sizes. macOS uses its own fixed scale, distinct from iOS Dynamic Type — confirmed anchors: Large Title 26pt down to body ~13pt, floor Caption 2 ~10pt. Source: developer.apple.com/design/human-interface-guidelines/typography. Gap — do not invent: the full intermediate scale (Title 1–3, Headline, Subhead, Footnote point values) is not confirmed in this pass; reconfirm on the HIG typography page or Xcode's SF font catalog before using an intermediate size verbatim.
2. No Dynamic Type on macOS — the platform ships fixed size variants per context (e.g. control sizes: regular/small/mini) instead of a user-adjustable type scale. Pick the variant that matches the control's context, don't apply an iOS Dynamic Type style.
3. Never draw a custom window chrome. Title bar, traffic lights, toolbar, and sidebar are system-drawn; the mockup should frame content inside a standard macOS window shape, not invent custom chrome. Source: developer.apple.com/design/human-interface-guidelines/windows.
4. Desktop tinting: background materials pick up a subtle tint from the desktop picture/wallpaper behind the window — reflect this as a soft, low-opacity tint layer in the mockup, not a flat opaque background. Source: developer.apple.com/design/human-interface-guidelines/materials.
5. Pointer feedback, not touch feedback: hover, highlight, and lift states on interactive elements (buttons, list rows) — macOS is pointer-driven, so every hoverable control needs a hover state in the mockup and handoff spec, unlike iOS/iPadOS touch-only flows. Source: developer.apple.com/design/human-interface-guidelines/pointing-devices.
6. Window sizing is a mockup convenience, not a spec. Unlike iOS device viewports, macOS windows are user-resizable — pick a reasonable default canvas (e.g. common productivity-app widths) for the mockup, but do not present it as an official fixed dimension; state that explicitly in the handoff spec.
7. Write the handoff spec per references/handoff-swiftui.md, adapted: macOS text sizes instead of Dynamic Type styles, hover/pressed/focused states (pointer, not touch), otherwise same named-token discipline.

Failure Handling

• Screenshot/preview tooling unavailable → describe the mockup in the handoff spec with exact pt values instead of blocking on a visual.
• A fact needed isn't in the references below → mark it "to reconfirm on developer.apple.com" in the output; never invent a number. This applies in particular to iOS/macOS spacing and corner-radius grids — neither is published as an official numeric scale; do not invent an 8pt-style grid for Apple platforms, point instead to Xcode's Design Resources / SF Symbols catalog as the source of truth to reconfirm against.

Output

• Device-framed (iOS) or window-framed (macOS) HTML mockup at exact viewport points/reasonable default canvas.
• handoff.md (or equivalent) with named tokens, text styles, semantic colors, sizing, states, spacing — ready for swift-expert.

Next → design-review (mockup-scoped: screenshot the mockup, verify contrast, no

full site audit loop).

References

| File | Purpose | |------|---------| | references/dynamic-type.md | Canonical iOS Dynamic Type scale (Large) — verified iosfontsizes.com | | references/semantic-colors.md | Canonical semantic color roles — verified WWDC19, still current | | references/viewports.md | Canonical iOS device viewports in points — verified ios-resolution.com | | references/liquid-glass.md | Canonical Liquid Glass facts — verified developer.apple.com, iOS 26 | | references/touch-targets.md | 44×44pt target — HIG-sourced, flagged for reconfirmation | | references/mockup.md | Device-frame HTML/CSS technique (safe areas, viewport-fit) | | references/handoff-swiftui.md | SwiftUI-ready handoff spec format |

Gap (not covered by any reference file, inlined above from HIG, flagged for a future references/macos.md): macOS type-size anchors, no-Dynamic-Type rule, system window chrome, desktop tinting, pointer states. Out of this pass's exclusive scope to create.