Enumerations

So far, we have covered two of the three types of classification in Swift: structure and class. The third classification is called enumeration. Enumerations are used to define a group of related values for an instance. For example, if we want values to represent one of the three primary colors, an enumeration is a great tool.

Basic declaration

An enumeration is made up of cases much like a switch and uses the keyword enum instead of struct or class. An enumeration for primary colors should look like this:

enum PrimaryColor {
    case Red
    case Green
    case Blue
}

You can then define a variable with this type and assign it one of the cases:

var color = PrimaryColor.Green

Note that, to use one of the values, we must use the name of the type followed by a dot (.) and then the specific case. If the type of the variable can be inferred, you can even leave out the enumeration name and just start with a dot:

var color = PrimaryColor.Green
color = .Red

During the assignment to .Red, the...