> ## Documentation Index > Fetch the complete documentation index at: https://substrate.docs.unknowncreatives.studio/llms.txt > Use this file to discover all available pages before exploring further. # iOS: Per-Mode Swift Token Files and the SubstrateKernel Package > Substrate emits per-mode Swift files declaring SubstrateSystemTokens in Display P3, plus SubstrateKernel — a SwiftPM port of the APCA, OKLCH, and CVD math. The Swift output has two halves. **Generated token files** hold statically resolved colors for each baked mode, and **SubstrateKernel** is a SwiftPM package containing a full port of the color math, for the cases where static values aren't enough. Which half you need depends on how dynamic your app is. Static files alone cover light, dark, and the two high-contrast modes. Anything continuous — a mid-track scheme position, CVD compensation, custom contrast — requires the kernel. *** ## What gets generated Each brand emits a directory under `generated/brands//swift/`: | File | Contents | | ----------------------------------- | --------------------------------------------------------------------- | | `system.light.gen.swift` | Resolved tokens at `scheme: 0`, `contrastFactor: 1.0` | | `system.dark.gen.swift` | Resolved tokens at `scheme: 1`, `contrastFactor: 1.0` | | `system.highContrast.gen.swift` | `scheme: 0`, `contrastFactor: 1.3` | | `system.darkHighContrast.gen.swift` | `scheme: 1`, `contrastFactor: 1.3` | | `brand.gen.swift` | Brand data the kernel evaluates | | `index.gen.swift` | Aggregate entry point: brand data plus resolved component descriptors | There is no `system.dimmed.gen.swift`. Dimmed sits mid-track at `scheme: 0.65`, so it has no endpoint to bake — producing it requires continuous track sampling through SubstrateKernel. See [Modes Overview](/modes/overview#the-five-presets). *** ## The token files Every per-mode file declares the same two top-level types: a `SubstrateSystemTokenSet` struct of exactly three colors, and a `SubstrateSystemTokens` enum of intent roles. This is example output for a fictional `acme` brand — `generated/brands/acme/swift/system.light.gen.swift`: ```swift theme={null} import SwiftUI public struct SubstrateSystemTokenSet { public let surface: Color public let text: Color public let border: Color public init(surface: Color, text: Color, border: Color) { self.surface = surface self.text = text self.border = border } } public enum SubstrateSystemTokens { public static let surface = SubstrateSystemTokenSet( surface: Color(.displayP3, red: 0.9588, green: 0.9594, blue: 0.9728, opacity: 1.0000), text: Color(.displayP3, red: 0.0424, green: 0.0427, blue: 0.0511, opacity: 1.0000), border: Color(.displayP3, red: 0.4431, green: 0.4436, blue: 0.4553, opacity: 1.0000) ) public static let brand = SubstrateSystemTokenSet( surface: Color(.displayP3, red: 0.3475, green: 0.1504, blue: 0.9177, opacity: 1.0000), text: Color(.displayP3, red: 0.3673, green: 0.1900, blue: 0.9455, opacity: 1.0000), border: Color(.displayP3, red: 0.5581, green: 0.5264, blue: 1.0000, opacity: 1.0000) ) } ``` Three things to note: * **Colors are Display P3**, not sRGB. The `Color(.displayP3, …)` initializer is deliberate — the solver works in a wide gamut and the output preserves it. * **Every intent is a surface/text/border triple.** There are no `primary`/`onPrimary` pairs and no separate foreground roles. * **There are no spacing or type-size constants.** Those live in component style descriptors and are resolved by the kernel. The intent roles in the enum are `surface`, `surfaceElevated`, `brand`, `neutral`, `danger`, `warning`, and `success`, plus whatever custom intents the brand declares. ### Selecting a mode Because all four files declare the *same* top-level names, they are **alternative artifacts, not siblings**. Adding two to one target collides on duplicate declarations. Pick one per build configuration, or wrap them behind your own conditional compilation. ```swift theme={null} import SwiftUI struct ContentView: View { var body: some View { VStack(spacing: 12) { Text("Balance due") .foregroundStyle(SubstrateSystemTokens.surface.text) Text("$42.00") .foregroundStyle(SubstrateSystemTokens.brand.text) } .padding() .background(SubstrateSystemTokens.surfaceElevated.surface) .overlay( RoundedRectangle(cornerRadius: 8) .stroke(SubstrateSystemTokens.surface.border) ) } } ``` If you want light and dark selected at runtime rather than at build time, either namespace the generated enums yourself or move to the kernel, which computes both from one brand definition. *** ## SubstrateKernel `packages/kernel-swift` is a SwiftPM package holding a pure-math port of the TypeScript kernel — no UI dependencies: | Source | Responsibility | | ----------------------- | ----------------------------------------------- | | `Apca.swift` | APCA contrast and the lightness solver | | `Oklch.swift` | OKLCH conversion and gamut mapping | | `Cvd.swift` | Machado simulation and hue redistribution | | `Warmth.swift` | The warmth transform | | `Track.swift` | Scheme-track evaluation at continuous positions | | `Pipeline.swift` | The warmth → cvd → apca pipeline | | `Preferences.swift` | `UserPreferences`, `CvdConfig`, `CvdType` | | `Surface.swift` | Base and derived surface computation | | `ColorResolve.swift` | Foreground, border, and surface resolution | | `StyleDescriptor.swift` | Component style descriptor types | | `BrandData.swift` | The brand model the kernel evaluates | | `Materials.swift` | Material and effect resolution | `UserPreferences` mirrors the web vector exactly, with the same defaults: ```swift theme={null} import SubstrateKernel var prefs = UserPreferences.defaults() prefs.scheme = 0.65 // dimmed — no baked file exists prefs.contrastFactor = 1.3 prefs.cvd = CvdConfig(type: .deutan, severity: 0.8) ``` The port is held to the TypeScript kernel by reference fixtures and per-brand conformance vectors, so a value computed in Swift matches the one the web runtime computes for the same inputs. *** ## Component descriptors Component styling ships as **data**, not code. Descriptors live in `generated/global/swift/components/`, with brand-specific overrides under the brand's own `swift/components/` directory. Each imports `SubstrateKernel` and describes a component as a tree of nodes and properties: ```swift theme={null} import SubstrateKernel public enum BadgeComponent { public static let style = ComponentStyleDescriptor( component: "badge", nodes: [ StyleNode( scope: .component, properties: [ StyleProperty(name: "padding-x", value: .spatial(2)), StyleProperty(name: "font-weight", value: .number(600)), StyleProperty(name: "shape", value: .radiusCapsule), StyleProperty(name: "transition-easing", value: .easing("brand")), ] ), StyleNode( scope: .role("primary"), background: ChannelParameters(alpha: 1), foreground: ChannelParameters(chroma: .multiplier(0), contrast: .auto) ), ] ) } ``` Spacing appears as `.spatial(2)` — a multiple of the space unit, resolved against the current `densityFactor` — rather than a fixed point value. That indirection is what lets density stay continuous. The per-brand `index.gen.swift` aggregates brand data and the resolved descriptor for each component into one entry point, keyed by component name. Every generated file carries a `@generated-substrate` header and is a build artifact. Never edit one — changes belong in the brand YAML, then regenerate with `npm run generate:tokens:swift` from a Substrate checkout. *** The Compose mirror of this output, plus the Material ColorScheme bridge. Why four files exist and dimmed doesn't, and what the preference vector controls.