斯威夫特 4 可编码数组的

Question

所以我有一个返回JSON对象数组的API路由。例如：

[
{"firstname": "Tom", "lastname": "Smith", "age": 31},
{"firstname": "Bob", "lastname": "Smith", "age": 28}
]

我正在尝试设想如何使用 Swift 中的新可编码功能将它们转换为类中的两个对象。因此，如果我有一个可编码的 person 类，我会想要接受该响应并让它给我两个人的对象。

我也在使用Alamofire来处理请求。

我该怎么做？到目前为止，我所看到的与可编码内容相关的所有内容都只允许 1 个对象。而且我还没有看到与Alamofire或Web框架的任何集成。

Answer 1

关于阿拉莫火5的更新：responseJSONDecodable.

struct Person: Codable {
let firstName, lastName: String
let age: Int
enum CodingKeys : String, CodingKey {
case firstName = "firstname"
case lastName = "lastname"
case age
}
}
Alamofire.request(request).responseJSONDecodable { (response: DataResponse<Person>) in
print(response)
}

---

Alamofire 4 暂时不会添加 Codable 支持(参见 #2177)，您可以改用此扩展：https://github.com/Otbivnoe/CodableAlamofire。

let jsonData = """
[
{"firstname": "Tom", "lastname": "Smith", "age": 31},
{"firstname": "Bob", "lastname": "Smith", "age": 28}
]
""".data(using: .utf8)!
struct Person: Codable {
let firstName, lastName: String
let age: Int
enum CodingKeys : String, CodingKey {
case firstName = "firstname"
case lastName = "lastname"
case age
}
}
let decoded = try! JSONDecoder().decode([Person].self, from: jsonData)

样品：http://swift.sandbox.bluemix.net/#/repl/59a4b4fad129044611590820

使用CodableAlamofire：

let decoder = JSONDecoder()
Alamofire.request(url).responseDecodableObject(keyPath: nil, decoder: decoder) { (response: DataResponse<[Person]>) in
let persons = response.result.value
print(persons)
}

keypath对应于 JSON 结构中包含结果的路径。例如：

{
"result": {
"persons": [
{"firstname": "Tom", "lastname": "Smith", "age": 31},
{"firstname": "Bob", "lastname": "Smith", "age": 28}
]
}
}

keypath=>results.persons

[
{"firstname": "Tom", "lastname": "Smith", "age": 31},
{"firstname": "Bob", "lastname": "Smith", "age": 28}
]

keypath=>nil(空keypath引发异常)

Answer 2

我设法将数据响应序列化为可编码的对象。

例如，您可能已经熟悉转换 json 对象[String: String]。该 json 对象需要使用json.data(using: .utf8)!转换为Data。

使用Alamofire，很容易获得该数据(或者至少这种数据对我有用，已经与.utf8兼容)，我可以使用这个已经可用的功能

func responseData(queue: DispatchQueue?, completionHandler: @escaping (DataResponse<Data>) -> Void) -> Self

然后只需将该数据用作completionHandler中Decoder的输入

let objek = try JSONDecoder().decode(T.self, from: data)

您也可以从文档中将其设置为一些通用序列化函数，稍作调整

泛型响应对象序列化

对此修改

func responseCodable<T: Codable>(
queue: DispatchQueue? = nil,
completionHandler: @escaping (DataResponse<T>) -> Void)
-> Self
{
let responseSerializer = DataResponseSerializer<T> { request, response, data, error in
guard error == nil else { return .failure(BackendError.network(error: error!)) }
guard let data = data else {
return .failure(BackendError.objectSerialization(reason: "data is not valid"))
}

do{
let objek = try JSONDecoder().decode(T.self, from: data!)
return .success(objek)
} catch let e {
return .failure(BackendError.codableSerialization(error: e))
}
}
return response(queue: queue, responseSerializer: responseSerializer, completionHandler: completionHandler)
}

示例结构

struct Fids: Codable {
var Status: Status?
var Airport: Airport?
var Record: [FidsRecord]
}

以这种方式使用函数

Alamofire.request("http://whatever.com/zzz").responseCodable { (response: DataResponse<Fids>) in
switch response.result{
case .success(let value):
print(value.Airport)
// MARK: do whatever you want
case .failure(let error):
print(error)
self.showToast(message: error.localizedDescription)
}
}

Answer 3

要解码为数组，为了清楚起见，您将响应放在类型别名中：

typealias ServiceResponseObject = [ResponseObject]

但随后您必须确认数组可编码：

extension Array: Decodable where Element: Decodable {}

这应该使一切正常。

Answer 4

使用 Codable 的 Swift 5

阿拉莫火通用响应

人物模型.swift (使用 SwiftyJsonAccelerator 创建)

import Foundation
class PersonModel: Codable {
enum CodingKeys: String, CodingKey {
case age
case firstname
case lastname   }
var age: Int?   var firstname: String?   var lastname: String?
init (age: Int?, firstname: String?, lastname: String?) {
self.age = age
self.firstname = firstname
self.lastname = lastname   }
required init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
age = try container.decodeIfPresent(Int.self, forKey: .age)
firstname = try container.decodeIfPresent(String.self, forKey: .firstname)
lastname = try container.decodeIfPresent(String.self, forKey: .lastname)   }
}

泛型获取响应

func genericGET<T: Decodable>(urlString: String, completion: @escaping (T?) -> ()) {
Alamofire.request(urlString)
.responseJSON { response in
// check for errors
switch response.result {
case .success(_):
do {
let obj = try JSONDecoder().decode(T.self, from: response.data!)
completion(obj)
} catch let jsonErr {
print("Failed to decode json:", jsonErr)
}
break
case .failure(_):

completion(nil)
break
}
}
}

调用此方法

genericGET(urlString: "YOUR_URL") { (persons: [PersonModel]?) in
print(persons?[0].firstname)
}