{
    "isHidden" : "Y"
}

protocol JSONStringConverterAvailable {
    static var defaultValue: Bool { get }
}

enum JSONDefaultWrapper {
    // ...
    
    // Property Wrapper - Optional String To Bool
    @propertyWrapper
    struct StringConverterWrapper<T: JSONStringConverterAvailable> {
        var wrappedValue: Bool = T.defaultValue
    }
    
    // ...
}

extension JSONDefaultWrapper.StringConverterWrapper: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        self.wrappedValue = (try container.decode(String.self)) == "Y"
    }
}

extension KeyedDecodingContainer {
    // ...
    
    func decode<T: JSONStringConverterAvailable>(_ type: JSONDefaultWrapper.StringConverterWrapper<T>.Type, forKey key: Key) throws -> JSONDefaultWrapper.StringConverterWrapper<T> {
        try decodeIfPresent(type, forKey: key) ?? .init()
    }
}

enum TypeCase {
    enum StringFalse: JSONStringConverterAvailable {
        // 기본값 - false
        static var defaultValue: Bool { false }
    }

    enum StringTrue: JSONStringConverterAvailable {
        // 기본값 - false
        static var defaultValue: Bool { true }
    }
}

enum JSONDefaultWrapper {
    //...
    typealias StringFalse = StringConverterWrapper<JSONDefaultWrapper.TypeCase.StringFalse>
    typealias StringTrue = StringConverterWrapper<JSONDefaultWrapper.TypeCase.StringTrue>
}

class Posting: Decodable {
    @JSONDefaultWrapper.StringFalse var stringFalseValue: Bool
    @JSONDefaultWrapper.StringTrue var stringTrueValue: Bool
}

enum `JSONDefaultWrapper` {
    // Property Wrapper - Optional Timestamp to Optinoal Date
    @propertyWrapper
    struct TimestampToOptionalDate {
        var wrappedValue: Date?
    }
}

extension JSONDefaultWrapper.TimestampToOptionalDate: Decodable {
    init(from decoder: Decoder) throws {
        let container = try decoder.singleValueContainer()
        let timestamp = try container.decode(Double.self)
        let date = Date.init(timeIntervalSince1970: timestamp)
        self.wrappedValue = date
    }
}

func decode(_ type: JSONDefaultWrapper.TimestampToOptionalDate.Type, forKey key: Key) throws -> JSONDefaultWrapper.TimestampToOptionalDate {
    try decodeIfPresent(type, forKey: key) ?? .init()
}

enum TypeCase {
    enum List<T: Decodable & ExpressibleByArrayLiteral>: JSONDefaultWrapperAvailable {
        // 기본값 - []
        static var defaultValue: T { [] }
    }
}

enum JSONDefaultWrapper {
    typealias EmptyList<T: Decodable & ExpressibleByArrayLiteral> = Wrapper<JSONDefaultWrapper.TypeCase.List<T>>
}