Enumerations are powerful language features that provide static typing for small set of frequently used values. They are used to make code more readable and less error-prone.

CaseIterable is a feature as when used on an enumeration, the compiler automatically generate a static collection of all the cases defined using the allCases property.

public protocol CaseIterable {

    /// A type that can represent a collection of all values of this type.
    associatedtype AllCases : Collection where Self == Self.AllCases.Element

    /// A collection of all values of this type.
    static var allCases: Self.AllCases { get }

enum CompassDirection: CaseIterable {
    case north, south, east, west

    // Code generated by the compiler
    static var allCases: AllCases {  
        return [.north, .south, .east, .west]

Note that CaseIterable requirements are enumerations with no associated values or @available attributes on its cases.

Thanks 🙂