Typography
Type is most of your UI. The system does the hard parts — optical sizes, tracking tables,
Dynamic Type — if you use its APIs. This skill covers when to trust the system, how to build
hierarchy deliberately, and what custom fonts owe you back.
When This Skill Activates
- Choosing fonts or building a type hierarchy for a screen or app
- Text truncating, cramping, or breaking under larger Dynamic Type sizes
- Adopting a custom/brand font (and keeping accessibility)
- Display typesetting: hero numbers, stats, editorial headlines
Rule 1: text styles first
Predefined styles (Large Title → Caption 2) are weight + size + leading combos with Dynamic
Type support built in — and different styles scale differently (body grows more than
footnote), which manual font sizes can't replicate.
- Build hierarchy from 2–3 text styles + emphasized variants (bold trait — the actual weight
varies per style: some go medium→semibold, others bold→heavy) before reaching for new fonts.
- Semantic colors + text styles together give dark mode, contrast, and Dynamic Type for free.
- macOS supports text styles (without Dynamic Type); design Mac type at 100% — no iOS-style
scaling assumptions.
Rule 2: let optical sizes and tracking work
- San Francisco blends Text→Display designs continuously between 17 and 28pt (below: sturdier
letterforms, looser tracking for legibility; above: tighter, more refined). System font APIs do
this automatically — hardcoded single-cut fonts don't.
- Tracking, not kerning, for letterspacing — tracking is size-specific and lets the OS
disable clashing features (ligatures). Override system tracking only in exceptional cases.
- Truncation pressure? Use
allowsTightening (default-tightening-for-truncation) instead of
manually squeezing — and prefer wrapping to truncating (line limit 0 on labels that matter).
- Line height moves only via leading traits: tight = −2pt, loose = +2pt (±1pt on watchOS); the
system adds leading automatically for tall scripts (Arabic, Devanagari).
The Dynamic Type ladder (WWDC24 10074)
12 sizes: 7 default + 5 accessibility (AX1–AX5). .body runs 17pt at default up to 53pt
at AX5 — roughly 3× taller, and layouts must expect that. Escalate in order:
- Text styles —
.font(.title) / preferredFont(forTextStyle:) +
adjusts-for-content-size, line count 0 so text wraps instead of truncating.
@ScaledMetric for the non-text riding alongside (icon frames, spacing); SF
Symbols scale via UIImage.SymbolConfiguration(textStyle:). Prioritize scaling
essential content over decoration.- Switch layout axis at accessibility sizes — branch on
dynamicTypeSize.isAccessibilitySize with AnyLayout(HStackLayout()) /
AnyLayout(VStackLayout()) (UIKit: flip the stack axis on
preferredContentSizeCategory.isAccessibilityCategory); give text the full line
width and relax lineLimit.
- Large Content Viewer — only for bars that legitimately can't grow: a tab bar takes
under 10% of screen height, and scaled to accessibility sizes it would eat almost a
quarter (WWDC24 10074). Scaling is always preferred; the viewer is the fallback, not
the fix.
Test at all 12 sizes (Xcode Previews → Variants → Dynamic Type Variants), not just the
biggest — mid-range accessibility sizes catch different wrap points.
The San Francisco family — pick by job
| Face |
Job |
| SF Pro |
The default; UI text everywhere |
| SF Pro Rounded |
Friendlier numerals/labels — widgets, health/fitness data |
| SF Compact |
watchOS (space-efficient counterpart) |
| SF Mono |
Code, tabular alignment |
| New York |
Serif — reading experiences, editorial contrast |
| SF Arabic / SF Arabic Rounded |
Arabic script with its own optical sizes |
The width axis (Condensed / Regular / Compressed / Expanded):
- Default Regular; every non-Regular choice is a legibility decision — check it.
- Condensed: fit more text comfortably (long headlines wrap one line fewer).
- Compressed: display-only density, not body text.
- Expanded: display typesetting AND small secondary labels (wide + loose tracking).
- Width is a fourth hierarchy lever beside weight, size, color; all widths share identical
vertical proportions, so mixing them never misaligns baselines. 2–3 styles are enough —
pair one width with contrasting weights, one weight with contrasting widths, or oppose both
for maximum display contrast.
Custom fonts: what you owe back
System fonts get Dynamic Type free; a brand font makes you the type engine:
- Scale with
UIFontMetrics(forTextStyle:).scaledFont(for:) + adjusts-for-content-size, or
SwiftUI Font.custom(_:size:relativeTo:); scale layout constants with @ScaledMetric.
- Test at the largest accessibility sizes — wrap to multiple lines rather than truncate.
- Verify script coverage for your locales; have a fallback plan for writing systems the brand
font doesn't cover (the system stacks:
system-ui, ui-rounded, ui-serif, ui-monospace
on the web).
- Budget for the maintenance: tracking tables, optical sizing, and weight ramps are things SF
does that a licensed font usually doesn't.
❌ Anti-patterns: hardcoded point sizes on user-facing text · kerning APIs for tracking jobs ·
custom font without relativeTo: (frozen size) · Compressed body text · truncation where
wrapping was possible.
Output Format
Type review: Element | Current (font/size/style) | Issue (hierarchy/scaling/legibility) | Fix
— check Dynamic Type at XXL + AX sizes before signing off; pairs with the contrast rules in
generators/accessibility-generator.
References
1---2name: typography3description: UI typography on Apple platforms — text styles and Dynamic Type, the San Francisco family (Pro/Rounded/Compact/Mono/New York + width axis), optical sizes, tracking vs kerning, leading adjustments, and custom-font scaling. Use when choosing fonts, building type hierarchy, fixing truncation/legibility, or making custom fonts respect Dynamic Type.4---5
6# Typography
7
8Type is most of your UI. The system does the hard parts — optical sizes, tracking tables,
9Dynamic Type — *if* you use its APIs. This skill covers when to trust the system, how to build
10hierarchy deliberately, and what custom fonts owe you back.
11
12## When This Skill Activates
13
14- Choosing fonts or building a type hierarchy for a screen or app
15- Text truncating, cramping, or breaking under larger Dynamic Type sizes
16- Adopting a custom/brand font (and keeping accessibility)
17- Display typesetting: hero numbers, stats, editorial headlines
18
19## Rule 1: text styles first
20
21Predefined styles (Large Title → Caption 2) are weight + size + leading combos with Dynamic
22Type support built in — and different styles scale *differently* (body grows more than
23footnote), which manual font sizes can't replicate.
24
25- Build hierarchy from 2–3 text styles + emphasized variants (bold trait — the actual weight
26 varies per style: some go medium→semibold, others bold→heavy) before reaching for new fonts.
27- Semantic colors + text styles together give dark mode, contrast, and Dynamic Type for free.
28- macOS supports text styles (without Dynamic Type); design Mac type at 100% — no iOS-style
29 scaling assumptions.
30
31## Rule 2: let optical sizes and tracking work
32
33- San Francisco blends Text→Display designs **continuously between 17 and 28pt** (below: sturdier
34 letterforms, looser tracking for legibility; above: tighter, more refined). System font APIs do
35 this automatically — hardcoded single-cut fonts don't.
36- **Tracking, not kerning**, for letterspacing — tracking is size-specific and lets the OS
37 disable clashing features (ligatures). Override system tracking only in exceptional cases.
38- Truncation pressure? Use `allowsTightening` (default-tightening-for-truncation) instead of
39 manually squeezing — and prefer wrapping to truncating (line limit 0 on labels that matter).
40- Line height moves only via leading traits: tight = −2pt, loose = +2pt (±1pt on watchOS); the
41 system adds leading automatically for tall scripts (Arabic, Devanagari).
42
43## The Dynamic Type ladder (WWDC24 10074)
44
4512 sizes: 7 default + 5 accessibility (AX1–AX5). `.body` runs 17pt at default up to 53pt
46at AX5 — roughly 3× taller, and layouts must expect that. Escalate in order:
47
481. **Text styles** — `.font(.title)` / `preferredFont(forTextStyle:)` +
49 adjusts-for-content-size, line count 0 so text wraps instead of truncating.
502. **`@ScaledMetric`** for the non-text riding alongside (icon frames, spacing); SF
51 Symbols scale via `UIImage.SymbolConfiguration(textStyle:)`. Prioritize scaling
52 essential content over decoration.
533. **Switch layout axis at accessibility sizes** — branch on
54 `dynamicTypeSize.isAccessibilitySize` with `AnyLayout(HStackLayout())` /
55 `AnyLayout(VStackLayout())` (UIKit: flip the stack axis on
56 `preferredContentSizeCategory.isAccessibilityCategory`); give text the full line
57 width and relax `lineLimit`.
584. **Large Content Viewer** — only for bars that legitimately can't grow: a tab bar takes
59 under 10% of screen height, and scaled to accessibility sizes it would eat almost a
60 quarter (WWDC24 10074). Scaling is always preferred; the viewer is the fallback, not
61 the fix.
62
63Test at all 12 sizes (Xcode Previews → Variants → Dynamic Type Variants), not just the
64biggest — mid-range accessibility sizes catch different wrap points.
65
66## The San Francisco family — pick by job
67
68| Face | Job |
69|---|---|
70| SF Pro | The default; UI text everywhere |
71| SF Pro Rounded | Friendlier numerals/labels — widgets, health/fitness data |
72| SF Compact | watchOS (space-efficient counterpart) |
73| SF Mono | Code, tabular alignment |
74| New York | Serif — reading experiences, editorial contrast |
75| SF Arabic / SF Arabic Rounded | Arabic script with its own optical sizes |
76
77**The width axis** (Condensed / Regular / Compressed / Expanded):
78
79- Default Regular; every non-Regular choice is a legibility decision — check it.
80- Condensed: fit more text comfortably (long headlines wrap one line fewer).
81- Compressed: display-only density, not body text.
82- Expanded: display typesetting AND small secondary labels (wide + loose tracking).
83- Width is a **fourth hierarchy lever** beside weight, size, color; all widths share identical
84 vertical proportions, so mixing them never misaligns baselines. 2–3 styles are enough —
85 pair one width with contrasting weights, one weight with contrasting widths, or oppose both
86 for maximum display contrast.
87
88## Custom fonts: what you owe back
89
90System fonts get Dynamic Type free; a brand font makes *you* the type engine:
91
92- Scale with `UIFontMetrics(forTextStyle:).scaledFont(for:)` + adjusts-for-content-size, or
93 SwiftUI `Font.custom(_:size:relativeTo:)`; scale layout constants with `@ScaledMetric`.
94- Test at the largest accessibility sizes — wrap to multiple lines rather than truncate.
95- Verify script coverage for your locales; have a fallback plan for writing systems the brand
96 font doesn't cover (the system stacks: `system-ui`, `ui-rounded`, `ui-serif`, `ui-monospace`
97 on the web).
98- Budget for the maintenance: tracking tables, optical sizing, and weight ramps are things SF
99 does that a licensed font usually doesn't.
100
101❌ Anti-patterns: hardcoded point sizes on user-facing text · kerning APIs for tracking jobs ·
102custom font without `relativeTo:` (frozen size) · Compressed body text · truncation where
103wrapping was possible.
104
105## Output Format
106
107Type review: `Element | Current (font/size/style) | Issue (hierarchy/scaling/legibility) | Fix`
108— check Dynamic Type at XXL + AX sizes before signing off; pairs with the contrast rules in
109`generators/accessibility-generator`.
110
111## References
112
113- https://developer.apple.com/videos/play/wwdc2020/10175/ (The details of UI typography)
114- https://developer.apple.com/videos/play/wwdc2022/110381/ (The expanded San Francisco family)
115- https://developer.apple.com/fonts/ (SF + New York downloads)
116- https://developer.apple.com/design/human-interface-guidelines/typography
117- Related skills: `design/sf-symbols` (symbols align to text styles), `foundation/attributed-string` (rich text mechanics), `generators/accessibility-generator`
rshankras