This tutorial belongs to the Swift series

Enumerations are a way to group a set of different options, under a common name.

Example:

enum Animal {
    case dog
    case cat
    case mouse
    case horse
}

This Animal enum is now a type.

A type whose value can only be one of the cases listed.

If you define a variable of type Animal:

var animal: Animal

you can later decide which value to assign it using this syntax:

var animal: Animal
animal = .dog

We can use enumerations in control structures like switches:

enum Animal {
    case dog
    case cat
    case mouse
    case horse
}

let animal = Animal.dog

switch animal {
case .dog: print("dog")
case .cat: print("cat")
default: print("another animal")
}

Enumerations values can be strings, characters or numbers.

You can also define an enum on a single line:

enum Animal {
    case dog, cat, mouse, horse
}

And you can also add type declaration to the enumeration, and each case has a value of that type assigned:

enum Animal: Int {
    case dog = 1
    case cat = 2
    case mouse = 3
    case horse = 4
}

Once you have a variable, you can get this value using its rawValue property:

enum Animal: Int {
    case dog = 1
    case cat = 2
    case mouse = 3
    case horse = 4
}

var animal: Animal
animal = .dog

animal.rawValue //1

Enumerations are a value type. This means they are copied when passed to a function, or when returned from a function. And when we assign a variable pointing to an enumeration to another variable.