CODEWITHSUNDEEP
enumsswift
Aaron Bratcher
Aaron Bratcher

Reputation: 6451

Return enum type based on string value in swift?

I'm trying to do the following in a playground to assign an enum type based on a string, but getting an error in the changeType function. How can I get this to work properly?

enum TransactionType {
    case purchase,charge
    case deposit,payment

    func description() -> String {
        switch self {
        case .purchase:
            return "purchase"
        case .charge:
            return "charge"
        case .deposit:
            return "deposit"
        case .payment:
            return "payment"
        }
    }

    func typeFromString(value:String) -> TransactionType   {
        switch value {
        case "charge":
            return .charge
        case "deposit":
            return .deposit
        case "payment":
            return .payment
        default:
            return .purchase
        }
    }
}

class Tester {
    var transactionType = TransactionType.purchase

    func changeType() {
        transactionType = TransactionType.typeFromString("charge")
    }
}

var tester = Tester()
print(tester.transactionType.description())

tester.changeType()
print(tester.transactionType.description())

Upvotes: 3

Views: 7927

Answers (2)

Antonio
Antonio

Reputation: 72760

The solution is simpler than you think:

enum TransactionType : String {
    case purchase = "purchase", charge = "charge"
    case deposit = "deposit", payment = "payment"
}

class Tester {
    var transactionType = TransactionType.purchase

    func changeType() {
        transactionType = TransactionType.fromRaw("charge")!
    }
}

var tester = Tester()
print(tester.transactionType.toRaw())

tester.changeType()
print(tester.transactionType.toRaw())

The trick is to set a raw value of String type, which defines the type associated to each enum case.

More info Raw Values in Enumerations

Upvotes: 3

Mundi
Mundi

Reputation: 80265

You can define the typeFromString method as static in order to avoid complications with optional values. After all, it just contains constants anyway. Simply add the word static before the func definition. 

static func typeFromString(value:String) -> TransactionType   {

Upvotes: 1

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