Enums

In Swift, an enumeration (enum) is a collection of set values that can be referenced throughout a program.

Syntax

enum MyEnum {
  Enumeration cases go here
}

To access specific cases in MyEnum, the dot operator . is used, following the case name:

MyEnum.case

Creating an enum and Examples

enum cases can be defined on separate lines:

enum Level {
  case beginner
  case intermediate
  case advanced
}

enum cases can also be written in a single line for simplicity:

enum Level {
  case beginner, intermediate, advanced
}

Raw Value

Raw values can be added for each case if a raw type is defined after the enum name and trailing colon :.

enum Bishop: String {
  case novice = "Beginner"
  case firstJob = "Magician"
  case secondJob = "Cleric"
  case thirdJob = "Priest"
}

The example above displays an enum, named Bishop, with a raw type of String and cases assigned to their respective raw values.

Associated Value

Associated values can be added to available cases.

enum MageAdvancementTree {
  case novice
  case firstJob(String)
  case secondJob(wizard: String)
  case thirdJob(mage: String)
  case fourthJob(arch: String)
}

var bishop = MageAdvancementTree.thirdJob(mage: "Priest")

print(bishop)
// Output: thirdJob(mage: "Priest")

An enum named MageAdvancementTree is created and most of its cases have associated values. Then, a bishop variable is declared as a MageAdvancementTree and sets the mage to a string, "Priest".

Accessing an enum and Examples

An enumeration can be accessed with the dot . syntax.

enum MageAdvancementTree {
  case novice, firstJob, secondJob, thirdJob, fourthJob
}

var bishop = MageAdvancementTree.thirdJob
bishop = .fourthJob

print(bishop)
// Output: fourthJob

When a variable is declared and set to an enumeration, it can be re-assigned to a different case value with the shortened dot syntax shown above.

Switch Case

A switch statement is another way to access values within an enumeration. In the example below, the bishop variable will be evaluated to match case .fourthJob because it was previously set to the fourthJob value. Access to the values in enum MageAdvancementTree is possible because bishop is already set to it.

switch bishop {
  case .novice:
    print("Beginner")
  case .firstJob:
    print("Magician")
  case .secondJob:
    print("Cleric")
  case .thirdJob:
    print("Priest")
  case .fourthJob:
    print("Bishop")
}
// Output: Bishop

Iterative

In the snippet below, MageAdvancementTree adopts the CaseIterable protocol which gives access to the allCases property. Using a for...in loop, each value within the enumeration can be accessed:

enum MageAdvancementTree: String, CaseIterable {
  case novice = "Beginner"
  case firstJob = "Magician"
  case secondJob = "Cleric"
  case thirdJob = "Priest"
  case fourthJob = "Bishop"
}

for job in MageAdvancementTree.allCases {
  print(job.rawValue)
}

This would output the raw values in MageAdvancementTree:

Beginner
Magician
Cleric
Priest
Bishop