In Swift, we can define simple types which have limited possible different values. These types are enumerations. We define them with the keyword enum. The following code is an example of this:

enum AnEnumeration {
     // the value definitions goes here
}

Here's another code that does this:

enum GameInputDevice 
     case keyboard, joystick, mouse
}

The code has three different enumeration cases. All cases may appear on a single line, such as in the preceding code, or even one by one on a line.

We can meet the following notation, because Swift infers the missing part:

var input = GameInputDevice.mouse
//... 
//later in the code
input = .joystick