iOS 10 Swift Programming Cookbook

Chapter 3. Measurements and Units

We have all been there! You need to convert one unit to another, and you begin your journey, most of the time, by Googling what the conversion should be. With iOS 10 SDK, you can now use some built-in structures to represent and convert your units.

The following classes and structures appear throughout this chapter:

Unit

The base class for all the units that are in the SDK itself. This class defines a symbol for the unit, such as m for meters.

Dimension

The class that inherits from Unit and defines the converter to be used between various units.

UnitLength, UnitMass, and the like

Basic units that inherit from Dimension. Each unit offers alternative ways of representing a particular measure, such as length or mass. Each unit also standardizes the various symbols for its measure, such as m for meters, km for kilometers, and smi for Scandinavian miles (with each Scandinavian mile being equal to 1 kilometer).

Measurement

The base structure for defining a value with a unit. Every measurement has a value of type Double and a unit of type Unit.

3.1 Converting Between and Working with Length Units

Problem

You want to be able to represent values with the unit of length, such as kilometers and miles, and would like to be able to perform some basic tasks on them, such as converting one unit to another, or adding and subtracting values represented in different units.

Solution

Follow these steps:

1. Represent your values first by constructing instances ...