Conversions between temperature scales are needed, especially in a world where three countries (the United States, the Cayman Islands and Liberia) use Fahrenheit in contrast to the Celsius scale.

Thankfully you don't have to remember the conversion formulae as an iOS developer. The Foundation framework comes to the rescue with its Measurement type.

A programmatic interface to convert measurements into different units, as well as calculate the sum or difference between two measurements.

The Foundation framework provides concrete Unit subclasses for many of the most common types of physical units. This includes temperature scales :)

let celsius = Measurement(value: 20.0, unit: UnitTemperature.celsius)
let fahrenheit = celsius.converted(to: .fahrenheit).value
let kelvin = celsius.converted(to: .kelvin).value
print(fahrenheit) // 67.99999999999571
print(c.converted(to: .kelvin).value)     // "293.15"

Use the MeasurementFormatter to present the conversion result to the end user.

A formatter that provides localized representations of units and measurements.

let formatter = MeasurementFormatter()
formatter.unitOptions = .providedUnit

let t = Measurement(value: 20.0, unit: UnitTemperature.celsius)
print(formatter.string(from: t)) //20°C
print(formatter.string(from: t.converted(to: .fahrenheit))) // 68°F
print(formatter.string(from: t.converted(to: .kelvin))) // 293.15 K

Let me finish my post with the following advice: Check the Unit subclasses below before your try implementing your own unit conversion 😊