[Swift] Decode a dictionary keyed with an enum

playground.swift

import Foundation

enum MyKey: String, Decodable, CodingKey {
    case one
    case two
}

struct Response: Decodable {
    let dictionary: [MyKey: String]
}


let json = """
{
"dictionary": {
    "one": "hi",
    "two": "okey"
}

}
"""

let decoded = try JSONDecoder().decode(Response.self, from: json.data(using: .utf8)!)

extension KeyedDecodingContainer  {
    func decode(_ type: [MyKey: String].Type, forKey key: Key) throws -> [MyKey: String] {
        let container = try self.nestedContainer(keyedBy: MyKey.self, forKey: key)
        return try container.allKeys
            .map { key in
                (key: key, value: try container.decode(String.self, forKey: key))
            }
            .reduce(into: [MyKey: String]()) {
                $0[$1.key] = $1.value
            }
    }
}