Help with enum methods in Swift

Question

Hello, so I've been playing around with code a little bit today and I wanted to write out a program in my playground that whenever you passed it one of the four main compass directions it would tell you which state you were heading towards so for example: North - New York, East - Carolina, South - Florida, West - California (I know theres two Carolinas lol) I believe I'm on the right track however whenever I pass a direction different than the one I have set in my initializer I still get the value from the initializer. Here's my code:

enum Direction {
    case North
    case East
    case South
    case West

    init() {
        self = .North

    }

    func directionBound(directionHeading: Direction) -> String {
        switch self {
        case .North:
            return "You're heading towards New York"
        case .East:
            return "You're heading towards the Carolinas"
        case .South:
            return "You're heading towards Florida"
        case .West:
            return "You're heading towards California"
        }
    }

}

var roadTrip = Direction()

roadTrip.directionBound(.East)

I understand theres probably aspects to this code which are unorthodox or just simply wrong and I would appreciate any type of constructive criticism you have for me! Thank you!

Answer 1 · 2015-01-22T00:00:49Z

January 22, 2015 12:00am

Hi Peter,

The reason you're getting the same value over and over is because your switch statement is referring to self which is the current enum instance value instead of the directionHeading parameter which you've defined within your directionBound method.

Also it's bad practise to not include a default case when using switches as if nothing matches your code may fail silently and can cause you hours of pain looking for a reason why, the other change is I've made your return type an optional that way we can ensure that a true direction is been returned otherwise we assume an unknown direction.

See the below.

enum Direction {
    case North, East, South, West

    init() {
        self = .North
    }

    func directionBound(directionHeading: Direction) -> String? {
        switch directionHeading {
        case .North:
            return "You're heading towards New York"
        case .East:
            return "You're heading towards the Carolinas"
        case .South:
            return "You're heading towards Florida"
        case .West:
            return "You're heading towards California"
        default:
            return nil
        }
    }
}

var roadTrip = Direction()

if let direction = roadTrip.directionBound(.East) {
    println(direction)
} else {
    println("Unknown direction")
}

Hope that helps.

Answer 2 · 2015-12-22T17:15:16Z

December 22, 2015 5:15pm

Need to assign a default, not use the Swift default in the enum. Hope this works!

enum Compass: Int {
    case North = 1
    case South = 2
    case East = 3
    case West = 4
}

let direction = Compass(rawValue: 2)

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Peter Fuhrey

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Help with enum methods in Swift

Peter Fuhrey

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Chris Shaw

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Ian Bowers

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