JSONのキーが "name" でも "NAME" でも受け入れてくれるDecodable #CodePiece

CodePiece.swift

func decodeJSON<T: Decodable>(_ t: T.Type, from string: String) {
    let data = string.data(using: .utf8)!

    let decoder = JSONDecoder()
    let s = try! decoder.decode(t, from: data)
    print(s)
}

struct Robustness: Decodable {
    let name: String

    private enum CodingKeys: CodingKey {
        case name
    }
    private enum NameCodingKeys: String, CodingKey {
        case lowerName = "name"
        case upperName = "NAME"
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: NameCodingKeys.self)

        name = try container.decodeIfPresent(String.self, forKey: .lowerName) ?? {
            try container.decode(String.self, forKey: .upperName)
        }()
    }
}

decodeJSON(Robustness.self, from: """
{
    "name": "名前",
}
""")

decodeJSON(Robustness.self, from: """
{
    "NAME": "名前",
}
""")

//decodeJSON(Robustness.self, from: """
//{
//    "name": 1,
//}
//""")
//error: Swift.DecodingError.typeMismatch(Swift.String, Swift.DecodingError.Context(codingPath: [Optional(__lldb_expr_21.Robustness.(NameCodingKeys in _4DF6FC7D4401F1058D53C11DCCEEFFE2).lowerName)], debugDescription: "Expected to decode String but found a number instead."))

//decodeJSON(Robustness.self, from: """
//{
//    "namae": "名前",
//}
//""")
//error: Swift.DecodingError.keyNotFound(__lldb_expr_5.Robustness.(NameCodingKeys in _2EA1F108365D333F4870AEDC03392B10).upperName, Swift.DecodingError.Context(codingPath: [Optional(__lldb_expr_5.Robustness.(NameCodingKeys in _2EA1F108365D333F4870AEDC03392B10).upperName)], debugDescription: "Key not found when expecting non-optional type String for coding key \"upperName\""))