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Jian Quan Ma
Jian Quan Ma

Reputation: 37

unable to convert Enum to string from Json in swift

I get the error:

Cannot initialize Role from invalid String value Mage

when I tried to interpret an array of string as enum type from a JSON file.

struct ChampionsData : Decodable{
    let id : String
    let key : String
    let info : Info
    let tags : [Role]
}

enum Role : String, CaseIterable, Decodable{
    case Tank = "you believe that last person standing wins"
    case Mage = "you like fantacies and tricking people"
    case Assasin = "you enjoy living with danger"
    case Fighter = "you are the warrior that built this town"
    case Support = "you are a reliable teammate that always appears where you are needed "
    case Marksman = "you tend to be the focus of the game, or the reason of victory or loss"

    enum CodingKeys: String, CodingKey {
        case mage = "Mage"
        case assassin = "Assassin"
        case tank = "Tank"
        case fighter = "Fighter"
        case support = "Support"
        case marksman = "Marksman"
    }
}

How can I parse it to a JSON object if I want to interpret tags as an array of Role enum type instead of an array of strings(or get rid of the error)?

Upvotes: 1

Views: 6641

Answers (1)

Razi Tiwana
Razi Tiwana

Reputation: 1435

Your JSON must be something like this

let jsonString = """
{
"id" :"asda",
"key" : "key asd",
"tags" : [
       "Mage",
       "Marksman"
]
}
"""

NOTE: I'm ignoring let info : Info here.

And from this string enum should be Mage, Marksman.. so on

But you have added them to be 

case Mage = "you like fantacies and tricking people"*

In Enum raw values are implicitly assigned as CodingKeys

Update your code to this

enum Role : String, Decodable {
    case tank = "Tank"
    case mage = "Mage"
    case assasin = "Assassin"
    case fighter = "Fighter"
    case support = "Support"
    case marksman = "Marksman"

    var value: String {
        switch self {
        case .tank:
            return "you believe that last person standing wins"
        case .mage:
            return "you like fantacies and tricking people"
        case .assasin:
            return "you enjoy living with danger"
        case .fighter:
            return "you are the warrior that built this town"
        case .support:
            return "you are a reliable teammate that always appears where you are needed"
        case .marksman:
            return "you tend to be the focus of the game, or the reason of victory or loss"
        }
    }
}

Then you can just use the value after decoding like this

let data = jsonString.data(using: .utf8)!

// Initializes a Response object from the JSON data at the top.
let myResponse = try! JSONDecoder().decode(ChampionsData.self, from: data)

print(myResponse.tags.first?.value as Any)

If we used the json mentioned in the start we will get 

"you like fantacies and tricking people"

Upvotes: 1

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