SwiftMeasurement

Fluent syntax and dimensional analysis for Foundation's Measurement types.

Quick Look

// Foundation
Measurement<UnitLength>(value: 42, unit: .kilometers)

// SwiftMeasurement
42.kilometers

Works with Int, Double, and Float across all 22 Foundation unit types.

Dimensional Analysis

DimensionalMeasurement tracks SI dimension exponents automatically, so you can multiply, divide, and root physical quantities across different unit types.

// Speed × Time = Distance
let distance = 60.0.kilometersPerHour * 2.hours
distance.convert(to: UnitLength.kilometers)  // 120.0 km

// Length × Length = Area
let area = 10.0.meters * 5.0.meters
area.convert(to: UnitArea.squareMeters)  // 50.0 m²

// Square root
area.squareRoot()?.asLength  // back to meters

Typed accessors (.asLength, .asArea, .asSpeed, .asEnergy, etc.) convert back to Measurement<T> — returns nil if the dimensions don't match.

Supported Units

All 22 unit types with example properties

Unit Type	Example Properties
UnitAcceleration	.metersPerSecondSquared, .gravity
UnitAngle	.degrees, .radians
UnitArea	.squareMeters, .squareKilometers, .hectares
UnitConcentrationMass	.gramsPerLiter, .milligramsPerDeciliter
UnitDispersion	.partsPerMillion
UnitDuration	.hours, .minutes, .seconds
UnitElectricCharge	.coulombs, .ampereHours
UnitElectricCurrent	.amperes, .milliamperes
UnitElectricPotentialDifference	.volts, .millivolts
UnitElectricResistance	.ohms, .kiloohms
UnitEnergy	.joules, .kilocalories, .kilowattHours
UnitFrequency	.hertz, .gigahertz
UnitFuelEfficiency	.litersPer100Kilometers, .milesPerGallon
UnitIlluminance	.lux
UnitInformationStorage	.bytes, .gigabytes, .terabytes
UnitLength	.kilometers, .meters, .miles, .feet
UnitMass	.kilograms, .grams, .pounds
UnitPower	.watts, .kilowatts, .horsepower
UnitPressure	.newtonsPerMetersSquared, .bars
UnitSpeed	.kilometersPerHour, .milesPerHour, .knots
UnitTemperature	.celsius, .fahrenheit, .kelvin
UnitVolume	.liters, .milliliters, .gallons

SwiftMeasurementCodable

A standalone product (no dependency on the SwiftMeasurement module) that encodes and decodes Measurement values as stable, portable JSON:

{"value": 21.5, "unit": "gram"}

unit is a CLDR core unit identifier (CLDR 48.2) — the same vocabulary JavaScript's Intl.NumberFormat accepts, so payloads stay locale-neutral and readable from any ecosystem. Foundation's built-in Measurement Codable shape (display symbols plus converter internals) is neither.

import Foundation
import SwiftMeasurementCodable

struct Recipe: Codable {
    var flour: CodableMeasurement<UnitMass>
    var oven: CodableMeasurement<UnitTemperature>
}

let recipe = Recipe(
    flour: Measurement(value: 500, unit: .grams).codable,
    oven: Measurement(value: 220, unit: .celsius).codable
)
let encoder = JSONEncoder()
encoder.outputFormatting = [.sortedKeys]   // stable key order on every platform
let data = try encoder.encode(recipe)
// {"flour":{"unit":"gram","value":500},"oven":{"unit":"celsius","value":220}}

let decoded = try JSONDecoder().decode(Recipe.self, from: data)
decoded.flour.measurement.converted(to: .ounces)

Add the product to your target:

.product(name: "SwiftMeasurementCodable", package: "SwiftMeasurement")

Strict or lenient. CodableMeasurement throws DecodingError on an unrecognized identifier. When your policy is "an unrecognized unit means the value is absent", decode RawMeasurement instead — it always succeeds, and typed access is failable:

let raw = try JSONDecoder().decode(RawMeasurement.self, from: json)
let mass: Measurement<UnitMass>? = raw.measurement(as: UnitMass.self)

Mapping primitives. The UnitIdentifierRepresentable protocol exposes both directions for custom wire shapes — UnitMass.grams.unitIdentifier == "gram" and UnitMass.unit(forIdentifier: "ounce") == .ounces — and lets you conform your own Dimension subclasses (see the protocol's documentation for the recipe).

Notes: encoding emits the measurement's current unit as-is (convert first to control the wire unit); all 22 Foundation Dimension types are covered for every constant with a regular CLDR 48.2 identifier; a few identifiers (e.g. bar) are valid CLDR but outside the smaller ECMA-402 sanctioned subset that Intl.NumberFormat formats.

Installation

Xcode: File > Add Package Dependencies > enter https://github.com/ken0nek/SwiftMeasurement.git

Package.swift:

dependencies: [
    .package(url: "https://github.com/ken0nek/SwiftMeasurement.git", from: "2.3.0")
]

License

MIT License. See LICENSE for details.