如果数据嵌套在Swift中，如何解码响应数据

我在解码响应数据时遇到问题。这是我的请求函数

  @IBAction func onGetCities(_ sender: UIButton) {

    guard let url = URL(string: "http://somelink.com/city-list") else { return }

    var request = URLRequest(url: url)
    request.httpMethod = "GET"

    let session = URLSession.shared
    let task = session.dataTask(with: request) { (data, response, error) in


        print(JSON(data))
        guard let data = data else { return }
        do{
            let cities = try JSONDecoder().decode([City].self, from: data)
            print(cities)
        }catch{

        }
    }
    task.resume()
}

城市结构

struct City: Decodable {
    let id: Int
    let city: String
}

这是响应数据，我想解码“项目”

---

您需要具有反映嵌套JSON的嵌套结构：

struct City: Decodable {
    let id: Int
    let city: String
}

struct ResponseObject: Decodable {
    let items: [City]
    let offset: Int
    let limit: Int
}

然后：

do {
    let result = try JSONDecoder().decode(ResponseObject.self, from: data)
    print(result)

    let cities = result.items
    print(cities)
} catch {
    print(error)
}

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .secondsSince1970

do {
    let result = try decoder.decode(ResponseObject.self, from: data)
    print(result)

    let cities = result.items
    print(cities)
} catch {
    print(error)
}

---

注意，在最初的示例中，您包含了一个JSON键，

updated_at

，它是自1970年以来以秒数表示的日期（标准UNIX表示）。因此，要解码：

struct City: Decodable {
    let id: Int
    let city: String
}

struct ResponseObject: Decodable {
    let items: [City]
    let offset: Int
    let limit: Int
    let code: Int
    let updatedAt: Date

    enum CodingKeys: String, CodingKey {
        case items, offset, limit, code
        case updatedAt = "updated_at"
    }
}

然后：

do {
    let result = try JSONDecoder().decode(ResponseObject.self, from: data)
    print(result)

    let cities = result.items
    print(cities)
} catch {
    print(error)
}

let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .secondsSince1970

do {
    let result = try decoder.decode(ResponseObject.self, from: data)
    print(result)

    let cities = result.items
    print(cities)
} catch {
    print(error)
}

---

还有一个问题，plz，建议使用吊舱吗？不。回到Swift 3，有些人会建议使用SwiftyJSON（虽然我个人从来都不喜欢），但

JSONDecoder

消除了这种需要。@AidogdyShahyrov-仅供参考，您修改后的问题对JSON做了一些修改，因此我在这里修改了代码以匹配。但希望它能说明基本思想，即使JSON格式的细节不太正确。感谢您从问题中删除代码屏幕快照！