Swift绝对可以处理任意可解码的JSON.这与任意可解码的东西不同. JSON无法编码所有可能的值.但是此结构将解码可以用JSON表示的所有内容，然后您就可以从那里以类型安全的方式探索它，而不必求助于Any之类的危险而笨拙的工具.

Swift can definitely handle an arbitrary JSON decodable. This isn't the same thing as an arbitrary decodable. JSON can't encode all possible values. But this structure will decode anything that can be expressed in JSON, and from there you can explore it in a type-safe way without resorting to dangerous and awkward tools like Any.

enum JSON: Decodable, CustomStringConvertible {
    var description: String {
        switch self {
        case .string(let string): return "\"\(string)\""
        case .number(let double):
            if let int = Int(exactly: double) {
                return "\(int)"
            } else {
                return "\(double)"
            }
        case .object(let object):
            return "\(object)"
        case .array(let array):
            return "\(array)"
        case .bool(let bool):
            return "\(bool)"
        case .null:
            return "null"
        }
    }

    var isEmpty: Bool {
        switch self {
        case .string(let string): return string.isEmpty
        case .object(let object): return object.isEmpty
        case .array(let array): return array.isEmpty
        case .null: return true
        case .number, .bool: return false
        }
    }

    struct Key: CodingKey, Hashable, CustomStringConvertible {
        var description: String {
            return stringValue
        }

        var hashValue: Int { return stringValue.hash }

        static func ==(lhs: JSON.Key, rhs: JSON.Key) -> Bool {
            return lhs.stringValue == rhs.stringValue
        }

        let stringValue: String
        init(_ string: String) { self.stringValue = string }
        init?(stringValue: String) { self.init(stringValue) }
        var intValue: Int? { return nil }
        init?(intValue: Int) { return nil }
    }

    case string(String)
    case number(Double) // FIXME: Split Int and Double
    case object([Key: JSON])
    case array([JSON])
    case bool(Bool)
    case null

    init(from decoder: Decoder) throws {
        if let string = try? decoder.singleValueContainer().decode(String.self) { self = .string(string) }
        else if let number = try? decoder.singleValueContainer().decode(Double.self) { self = .number(number) }
        else if let object = try? decoder.container(keyedBy: Key.self) {
            var result: [Key: JSON] = [:]
            for key in object.allKeys {
                result[key] = (try? object.decode(JSON.self, forKey: key)) ?? .null
            }
            self = .object(result)
        }
        else if var array = try? decoder.unkeyedContainer() {
            var result: [JSON] = []
            for _ in 0..<(array.count ?? 0) {
                result.append(try array.decode(JSON.self))
            }
            self = .array(result)
        }
        else if let bool = try? decoder.singleValueContainer().decode(Bool.self) { self = .bool(bool) }
        else {
            self = .null
        }
    }

    var objectValue: [String: JSON]? {
        switch self {
        case .object(let object):
            let mapped: [String: JSON] = Dictionary(uniqueKeysWithValues:
                object.map { (key, value) in (key.stringValue, value) })
            return mapped
        default: return nil
        }
    }

    var arrayValue: [JSON]? {
        switch self {
        case .array(let array): return array
        default: return nil
        }
    }

    subscript(key: String) -> JSON? {
        guard let jsonKey = Key(stringValue: key),
            case .object(let object) = self,
            let value = object[jsonKey]
            else { return nil }
        return value
    }

    var stringValue: String? {
        switch self {
        case .string(let string): return string
        default: return nil
        }
    }

    var doubleValue: Double? {
        switch self {
        case .number(let number): return number
        default: return nil
        }
    }

    var intValue: Int? {
        switch self {
        case .number(let number): return Int(number)
        default: return nil
        }
    }

    subscript(index: Int) -> JSON? {
        switch self {
        case .array(let array): return array[index]
        default: return nil
        }
    }

    var boolValue: Bool? {
        switch self {
        case .bool(let bool): return bool
        default: return nil
        }
    }
}

使用此功能，您可以执行以下操作:

With this, you can do things like:

let bilboJSON = """
{"value":"Bilbo"}
""".data(using: .utf8)!

let bilbo = try! JSONDecoder().decode(JSON.self, from: bilboJSON)
bilbo["value"]  // "Bilbo"

let javaJSON = """
{"value":["[Ljava.lang.Object;",["Bilbo",111]]}
""".data(using: .utf8)!

let java = try! JSONDecoder().decode(JSON.self, from: javaJSON)
java["value"]?[1]   // ["Bilbo", 111]
java["value"]?[1]?[0]?.stringValue  // "Bilbo" (as a String rather than a JSON.string)

?的泛滥有些难看，但是在我的实验中使用throws并不能真正使界面更好(特别是因为下标不能抛出).建议根据您的特定用例进行一些调整.

The proliferation of ? is somewhat ugly, but using throws on this doesn't really make the interface much nicer in my experiments (particularly because subscripts can't throw). Some tweaking may be advisable based on your particular use cases.