IosCustomFontDynamicType [rule] v1.0.0

Custom fonts must be scaled with Dynamic Type by registering them via UIFontMetrics.scaled(for:) in UIKit or Font.custom(_:relativeTo:) in SwiftUI, anchored to a semantic text style.

Applies To

all non-system typefaces used in an iOS app

IosCustomFontDynamicType [rule] v1.0.0

Custom fonts must be scaled with Dynamic Type by registering them via UIFontMetrics.scaled(for:) in UIKit or Font.custom(_:relativeTo:) in SwiftUI, anchored to a semantic text style.

Applies To

all non-system typefaces used in an iOS app

Examples

• SwiftUI: Font.custom('BrandSans', size: 17, relativeTo: .body) — scales with the body text style.
• UIKit: UIFontMetrics(forTextStyle: .body).scaledFont(for: UIFont(name: 'BrandSans', size: 17)!).
• Verify: set Dynamic Type to a large size in Settings → Accessibility; custom-font text must grow proportionally.

Rationale

Custom fonts that do not scale break accessibility for users who rely on larger text sizes. UIFontMetrics and Font.custom(_:relativeTo:) are the only correct hooks for propagating Dynamic Type scale to a non-system typeface.

Applies To

all non-system typefaces used in an iOS app