Nesting Enums

If you have specific sub type requirements, you can also logically nest enums in an enum. This allows you to contain specific information on your enum case within the actual enum. Imagine a character in an RPG. Each character can have a weapon, all characters have access to the same set of weapons. All other instances in the game do not have access to those weapons (they're trolls, they just have clubs).

enum Character {

   enum Weapon {

     case bow

     case sword

     case lance

     case dagger

   }

   enum Helmet {

     case wooden

     case iron

     case diamond

   }

   case thief

   case warrior

   case knight

}

Now you have a hierachical system to describe the various items that your character has access to.

let character = Character.thief

let weapon = Character.Weapon.bow

let helmet = Character.Helmet.iron

If you add initializers for the nested enum types, you can still benefit from not having to type out the the long description. Imagine a function that calculates how strong a character is, based on the character, the weapon, and the helmet:

func strength(of character: Character, 

      with weapon: Character.weapon, 

      and armor: Character.Helmet) {

      return 0

}



// You can still call it like this:

strength(of: .thief, with: .bow, and: .wooden)

This is still really clear and easy to understand.

Containing Enums

In a similar vein, you can also embed enums in structs or classes. Continuing with our previous example:

struct Character {

    enum CharacterType {

     case thief

     case warrior

     case knight

   }

   enum Weapon {

     case bow

     case sword

     case lance

     case dagger

   }

   let type: CharacterType

   let weapon: Weapon

}



let warrior = Character(type: .warrior, weapon: .sword)

This really helps in keeping related information together.