swift - 在动态类型/对象上使用 Codable

Question

嗨，我有以下结构嵌套在从 api 调用返回的更大结构中，但我无法对这部分进行编码/解码。我遇到的问题是 customKey 和 customValue 都是动态的。

{
    "current" : "a value"
    "hash" : "some value"
    "values": {
        "customkey": "customValue",
        "customKey": "customValue"
    }
}

我尝试了类似var values: [String:String]但这显然不起作用，因为它实际上不是一个[String:String].

Answer 1

由于您链接到我对另一个问题的回答，我将扩展该问题以回答您的问题。

事实是，如果您知道在哪里查看，所有键在运行时都是已知的：

struct GenericCodingKeys: CodingKey {
    var intValue: Int?
    var stringValue: String

    init?(intValue: Int) { self.intValue = intValue; self.stringValue = "\(intValue)" }
    init?(stringValue: String) { self.stringValue = stringValue }

    static func makeKey(name: String) -> GenericCodingKeys {
        return GenericCodingKeys(stringValue: name)!
    }
}


struct MyModel: Decodable {
    var current: String
    var hash: String
    var values: [String: String]

    private enum CodingKeys: String, CodingKey {
        case current
        case hash
        case values
    }

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        current = try container.decode(String.self, forKey: .current)
        hash = try container.decode(String.self, forKey: .hash)

        values = [String: String]()
        let subContainer = try container.nestedContainer(keyedBy: GenericCodingKeys.self, forKey: .values)
        for key in subContainer.allKeys {
            values[key.stringValue] = try subContainer.decode(String.self, forKey: key)
        }
    }
}

用法：

let jsonData = """
{
    "current": "a value",
    "hash": "a value",
    "values": {
        "key1": "customValue",
        "key2": "customValue"
    }
}
""".data(using: .utf8)!

let model = try JSONDecoder().decode(MyModel.self, from: jsonData)

Answer 2

简化的答案，它与字典 [String: String] 一起使用（instatead of String 你可以使用其他结构）：

let jsonData = """
{
    "current": "a value",
    "hash": "a value",
    "values": {
        "key1": "customValue",
        "key2": "customValue"
    }
}
""".data(using: .utf8)!

struct MyModel: Decodable {
    var current: String
    var hash: String
    var values: [String: String]
}

let model = try JSONDecoder().decode(MyModel.self, from: jsonData)

for (key,value) in model.values {
    print("key: \(key) value: \(value)")
}