| TestsTested | ✓ |
| LangLanguage | SwiftSwift |
| License | MIT |
| ReleasedLast Release | Mar 2016 |
| SPMSupports SPM | ✗ |
Maintained by Otavio Cordeiro.
(…) for example, length is a physical quantity. The metre is a unit of length that represents a definite predetermined length. When we say 10 metres (or 10 m), we actually mean 10 times the definite predetermined length called metre – Wikipedia
UnitKit is a pretty simple framework for creating, converting, and comparing units and physical quantities in Swift.
It supports quantity operations and comparison, and unit conversion for several units right out of the box. Feel free to submit pull requests in case UnitKit doesn’t have support for the unit you need.
On the technical side, UnitKit implements the Quantity Pattern, described by Martin Fowler in this article entitled Quantity.
With UnitKit it’s possible to add and subtract quantities as well as multiply and divide quantities by scalars.
When adding and subtracting quantities, the result will be of the same unit of the first quantity. Below, the result is in meters because 5 meters is the first quantity in the operation.
let fiveMeters = Quantity(5, unit: Length.meter)
let tenInches = Quantity(10, unit: Length.inch)
let twoYards = Quantity(2, unit: Length.yard)
var result = fiveMeters + tenInches
// 5.254 m
result = fiveMeters + tenInches - twoYards
// 3.4252 m
result = 2 * fiveMeters
// 10.0 m
result = tenInches / 2
// 5.0 inUnit conversion respects the category of the unit. Conversion between two different unit categories will result in compilation error.
In other words, length can be converted into length, area into area, and so on.
let twoYards = Quantity(2, unit: Length.yard)
let result = twoYards.convertTo(Length.meter)
// 1.8288 mThe following comparisons are present for quantities >, >=, <, <=, ==, and ~==.
The == operator should be used to compare physical quantities that express the same unit.
let tenMeters = Quantity(10, unit: Length.meter)
let anotherTenMeters = 2 * Quantity(5, unit: Length.meter)
let result = tenMeters == anotherTenMeters
// true
let tenMeters = Quantity(10, unit: Length.meter)
let fifteenMeters = 3 * Quantity(5, unit: Length.meter)
let result = tenMeters == fifteenMeters
// falseThe ~== operator should be used to compare physical quantities from the same category.
let speed_kph = Quantity(72, unit: kilometerPerHour)
let speed_mph = Quantity(44.7390837508948, unit: milePerHour)
let result = speed_kph ~== speed_mph
// trueThe goal for UnitKit is to have most of the Units of Measurement listed on this Wikipedia page implemented. For now, only the most common units are implemented.
But UnitKit was designed to allow customization. It’s possible to extend a category to add new units and even create new categories with their own units.
To extend an existing category, create a extension with the new unit definition. Example:
extension Volume {
static let gole = Unit<Volume>(name: "gole de cerveja", symbol: "gol", ratio: 6e-1)
}
let umGole = Quantity(1, unit: Volume.gole)
let result = umGole.convertTo(Volume.liter)
// 0.6 lTo create a new category, create a struct for the new category and implement the unit definitions. Example:
struct Force {
static let newton = Unit<Force>(name: "newton", symbol: "N", ratio: 1)
static let poundForce = Unit<Force>(name: "pound force", symbol: "lbf", ratio: 4448e-3)
}
let force = Quantity(0.3, unit: Force.newton)
let result = force.convertTo(Force.poundForce)
// 0.0674460431654676 lbfWant to contribute? Sweet!
git checkout -b my_awesome_feature)git commit -am "Add new awesome feature")git push origin my_awesome_feature)Copyright © 2016 Otavio Cordeiro. All rights reserved.
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