Difference between associated and raw values in swift enumerations

Question

Swift enumerations have both associated and raw values. But the use cases of these values is not clear to me. So I would really appreciate if anyone can explain the difference b

Answer 1

In Swift, an enum cannot have both raw values and associated values at the same time.

Raw Values

enum Color: String {
    case white = "#ffffff"
    case black = "#000000"
}

A "raw value" is an unique identifier of a type. It means that you are able to construct your type by ID. For example:

XCTAssertEqual(Color.white, Color(rawValue: "#ffffff"))

To get raw value use

Color.white.rawValue

Associated Values

enum Color {
    case white
    case black
    
    case custom(hex: String)
}

Swift's "associated values" allows you to add additional information into enum that can be defined dynamically. Please note when we introduce "associated values", we omit the "raw values" and add a type annotation. This makes it impossible to use the "raw value" to reconstruct your type, because it is now set up dynamically.

You can read the "associated value" as follows:

let myColor = Color.custom(hex: "#ff00ff")
    
switch myColor {
case .custom(let hex):
    print("custom color hex:\(hex)") //#ff00ff
case .white:
    print("white color")
case .black:
    print("black color")
}

Please note that Objective-C does not support Swift's enum(except Int-bound)