如何使用Swift 4.2正确编码JSON响应？

struct ResponseData: Codable {
    let name: String
    let age: Int
}

let responseData = ResponseData(name: "John", age: 25)
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
encoder.dateEncodingStrategy = .iso8601

do {
    let jsonData = try encoder.encode(responseData)
    let jsonString = String(data: jsonData, encoding: .utf8)
    print(jsonString)
} catch {
    print("Encoding failed: \(error)")
}

let jsonString = "{\"name\":\"John\",\"age\":25}"
let jsonData = jsonString.data(using: .utf8)

let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
decoder.dateDecodingStrategy = .iso8601

do {
    let responseData = try decoder.decode(ResponseData.self, from: jsonData!)
    print(responseData)
} catch {
    print("Decoding failed: \(error)")
}