如何在 Swift 5 中使用 Alamofire 解析 json

【问题标题】：How to parse json with Alamofire in Swift 5如何在 Swift 5 中使用 Alamofire 解析 json
【发布时间】：2019-11-14 11:21:21
【问题描述】：

我是 iOS 编程语言的新手，我正在尝试将数据从 WordPress JSON 提取到表格视图中。我遇到了错误：

'Any' 类型的值没有下标

当我尝试实例化数组的对象时。

这是 JSON：

[
 {
    "id": 1352,
    "date": "2019-10-16T09:30:39",
    "date_gmt": "2019-10-16T09:30:39",
    "guid": {
        "rendered": "https://wepress.comm-it.it/ddjhgtr/"
    },
    "modified": "2019-10-16T13:23:41",
    "modified_gmt": "2019-10-16T13:23:41",
    "slug": "ddjhgtr",
    "status": "publish",
    "type": "post",
    "link": "https://wepress.comm-it.it/ddjhgtr/",
    "title": "ddjhgtr",
    "content": "eryyreytyvggjggvhghhh",
    "excerpt": "eryyreyty",
    "author": 2,
    "featured_media": {
        "id": 1418,
        "url": "https://wepress.comm-it.it/wp-content/uploads/2019/10/10-62.jpeg"
    },
    "comment_status": "open",
    "ping_status": "open",
    "sticky": false,
    "template": "",
    "format": "standard",
    "meta": [],
    "categories": [
        {
            "id": 1,
            "name": "Uncategorized",
            "description": ""
        }
    ],
    "tags": [],
    "_links": {
        "self": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts/1352"
            }
        ],
        "collection": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts"
            }
        ],
        "about": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/types/post"
            }
        ],
        "author": [
            {
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/users/2"
            }
        ],
        "replies": [
            {
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/comments?post=1352"
            }
        ],
        "version-history": [
            {
                "count": 3,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts/1352/revisions"
            }
        ],
        "predecessor-version": [
            {
                "id": 1419,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts/1352/revisions/1419"
            }
        ],
        "wp:featuredmedia": [
            {
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/media/1418"
            }
        ],
        "wp:attachment": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/media?parent=1352"
            }
        ],
        "wp:term": [
            {
                "taxonomy": "category",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/categories?post=1352"
            },
            {
                "taxonomy": "post_tag",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/tags?post=1352"
            },
            {
                "taxonomy": "difficulty-level-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/difficulty-level-course?post=1352"
            },
            {
                "taxonomy": "category-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/category-course?post=1352"
            },
            {
                "taxonomy": "location-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/location-course?post=1352"
            },
            {
                "taxonomy": "duration-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/duration-course?post=1352"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
    }
 },

....（许多其他新闻对象）

{
    "id": 774,
    "date": "2019-10-07T07:30:51",
    "date_gmt": "2019-10-07T07:30:51",
    "guid": {
        "rendered": "https://wepress.comm-it.it/name-here/"
    },
    "modified": "2019-10-07T07:30:51",
    "modified_gmt": "2019-10-07T07:30:51",
    "slug": "name-here",
    "status": "publish",
    "type": "post",
    "link": "https://wepress.comm-it.it/name-here/",
    "title": "name here",
    "content": "desc here",
    "excerpt": "desc here",
    "author": 2,
    "featured_media": null,
    "comment_status": "open",
    "ping_status": "open",
    "sticky": false,
    "template": "",
    "format": "standard",
    "meta": [],
    "categories": [
        {
            "id": 1,
            "name": "Uncategorized",
            "description": ""
        }
    ],
    "tags": [],
    "_links": {
        "self": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts/774"
            }
        ],
        "collection": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts"
            }
        ],
        "about": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/types/post"
            }
        ],
        "author": [
            {
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/users/2"
            }
        ],
        "replies": [
            {
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/comments?post=774"
            }
        ],
        "version-history": [
            {
                "count": 0,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/posts/774/revisions"
            }
        ],
        "wp:attachment": [
            {
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/media?parent=774"
            }
        ],
        "wp:term": [
            {
                "taxonomy": "category",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/categories?post=774"
            },
            {
                "taxonomy": "post_tag",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/tags?post=774"
            },
            {
                "taxonomy": "difficulty-level-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/difficulty-level-course?post=774"
            },
            {
                "taxonomy": "category-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/category-course?post=774"
            },
            {
                "taxonomy": "location-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/location-course?post=774"
            },
            {
                "taxonomy": "duration-course",
                "embeddable": true,
                "href": "https://wepress.comm-it.it/wp-json/wp/v2/duration-course?post=774"
            }
        ],
        "curies": [
            {
                "name": "wp",
                "href": "https://api.w.org/{rel}",
                "templated": true
            }
        ]
      }
  }
]

目前我有兴趣获取这些“对象”的图像 (featured_media)、标题和内容，并将它们放入 tableView。事实上，这里是我为他们创建的结构：

新闻表示包含在 JSON 数组中的结构

struct News {
    public var id: Int
    public var title: String
    public var content: String
    public var image: FeaturedMedia
}

struct FeaturedMedia {
    public var id: Int
    public var url: String
}

这是UITableViewCell 类：

import UIKit

class NewsTableViewCell: UITableViewCell {
    @IBOutlet weak var newsImage: UIImageView!
    @IBOutlet weak var newsTitle: UILabel!
    @IBOutlet weak var newsContent: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
    }
}

这里是UITableViewController 类：

import UIKit
import Alamofire
import Alamofire_SwiftyJSON
import SwiftyJSON

class NewsTableViewController: UITableViewController {

    var newsList: [News] = [News]()

    func parseJsonNews() {
        DispatchQueue.main.async {
            Alamofire.request("link request", method: .get).responseJSON { (response) in
                switch response.result {
                case .success(let value):
                    let news = [value]
                    print(news) // here in console it prints correctly the json, starting with [<__NSArrayI 0x6000001a9e60 ....
                    for new in news {
                        let title = new["title"]
                        print(title)
                    }
                    print(newsss)

                    self.tableView.reloadData()
                case.failure(let error):
                    print(error.localizedDescription)
                }
            })
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        parseJsonNews()
    }

    // MARK: - Table view data source

    override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.newsList.count
    }


    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "newsCell", for: indexPath) as? NewsTableViewCell


        // Configure the cell...
        let imageUrl = URL.init(string: newsList[indexPath.row].featuredMedia.url)
        cell?.newsTitle.text = self.newsList[indexPath.row].title
        cell?.newsContent.text = self.newsList[indexPath.row].content
        cell.newsImage.load(url: imageUrl!)
        return cell!
    }
}

extension UIImageView {
    func load(url: URL) {
        DispatchQueue.global().async { [weak self] in
            if let data = try? Data(contentsOf: url) {
                if let image = UIImage(data: data) {
                    DispatchQueue.main.async {
                        self?.image = image
                    }
                }
            }
        }
    }
}

寻找解决方案，我刚刚找到了许多解析字典 JSON 的方法，但在这种情况下，它是一个数组，所以我修改了您在 parseJsonNews 方法处阅读的代码，但它不能正常工作。

如果有任何帮助，将不胜感激。

【问题讨论】：

  • 也许这对你有用 -> medium.com/better-programming/json-parsing-in-swift-2498099b78f
  • 这一行打印什么？ print(title)
  • 你到底在哪一行得到错误？
  • 您需要使用 JsonDecoder 来解析响应中的值。您采用的结构应该是可编码的，然后您可以使用 JSONDecoder 将它们解码到您的模型类中。如果您需要有关 JSONDecoder 代码的帮助，请告诉我。
  • @FaysalAhmed 不，它不打印任何东西

标签： ios json swift xcode


【解决方案1】：

您可以像这样使用Codable 进行解码：

let data = try? JSONDecoder().decode([DummyData].self, from: jsonData)

但首先，您的所有模型都必须符合Codable 协议。例如：

struct DummyData: Codable {
    let id: Int
    let date, dateGmt: String
    let modified, modifiedGmt, slug, status: String
    let type: String
    let link: String
    let title, content, excerpt: String
    let author: Int
    let commentStatus, pingStatus: String
    let sticky: Bool
    let template, format: String

    enum CodingKeys: String, CodingKey {
        case id, date
        case dateGmt = "date_gmt"
        case modified
        case modifiedGmt = "modified_gmt"
        case slug, status, type, link, title, content, excerpt, author
        case commentStatus = "comment_status"
        case pingStatus = "ping_status"
        case sticky, template, format
    }
}

【讨论】：

【解决方案2】：

有几点：

  1. 错误value of type 'Any' has no subscripts，指的是你的行let title = new["title"]。 .success枚举中Alamofire的响应结果返回Any的类型， 这适用于您获取的整个数据数组。 swift 中的Any 类型没有任何subscripts 实现（即：您不能使用以下语法obj['MY_VAR_NAME'] 访问其中的变量。

  2. 为了像let title = new["title"] 这样从news 对象访问title，您必须首先将对象转换为字典，可以这样完成：

            // ... 
        let news = [value]
        print(news)
        for new in news {
            if let obj = new as? [String: Any] {
                let title = obj["title"]
                print(title)
            }
        }
        // ...

  3. 为了解析/使用您的自定义结构，它们必须首先遵守 swift 的Codable 协议。

     /// Example show only News, but the same which be used for FeaturedMedia
  struct News {
    public var id: Int
    public var title: String
    public var content: String
    public var image: FeaturedMedia?
    init?(jsonString: String) {
       guard let data = jsonString.data(using: .utf8) else {
             return nil
       }
       guard let object = News(data: data) else {
                return nil
       }
       self = object
   }

   init?(data: Data) {
       guard let object = try? JSONDecoder().decode(News.self, from:  
        data) else {
              return nil
       }
      self = object
  }
  // Optional, for custom key names (i.e: "image" instead of "featured_media"
  private enum CodingKeys: String, CodingKey {
         case id = "id"
         case image = "featured_media"
       // etc..
  }

}

完成第 4 步后，您可以像这样初始化对象：

            // ... 
            let news = [value]
            print(news)
            for new in news {
                if let obj = News(new) {
                  /// obj is now a News object
                    let title = obj.title
                    print(title)
                }
            }
            // ...

如果您正在寻求更多信息（例如初始化整个数组） 退房this 我希望我已经把事情弄清楚了:)

【讨论】：

    【解决方案3】： 
     func ComplainData() {
     let semaphore = DispatchSemaphore(value: 0)
     var request = URLRequest(url: URL(string: Constant.localBaseurl2 + "compID") !, timeoutInterval: Double.infinity)
     request.httpMethod = "GET"
     let task = URLSession.shared.dataTask(with: request) {
         data,
         response,
         error in
         if let response = response {
             let nsHTTPResponse = response as!HTTPURLResponse
             print(nsHTTPResponse)
         }

         if let error = error {
             print("\(error)")
             return
         }

         if let data = data {
             DispatchQueue.main.async {
                 let decoder = JSONDecoder()
                 decoder.keyDecodingStrategy = .convertFromSnakeCase //or any other Decoder\

                 do {
                     let jsonDecoder = JSONDecoder()
                     let memberRecord =
                         try jsonDecoder.decode(COMPLAINTSVC.GetComplaints.self, from: data)
                     print(memberRecord.message)

                     for detailData in memberRecord.message {
                         print(detailData)
                     }
                 } catch {
                     print(error.localizedDescription)
                 }
             }
         }
         semaphore.signal()
     }
     task.resume()
     semaphore.wait()
 }

    【讨论】：

    • 您应该为答案添加解释。
    • How to parse json with Alamofire 你的回答中没有使用 Alamofire，这是题外话。
    猜你喜欢
    • 2020-02-23
    • 1970-01-01
    • 1970-01-01
    • 1970-01-01
    • 2018-09-05
    • 1970-01-01
    • 2019-05-12
    • 2020-11-19
    • 1970-01-01
    相关资源
    最近更新 更多
    热门标签
    Java Python linux javascript Mysql C# Docker 算法 前端 SpringBoot Redis Vue spring 设计模式 .net core .net kubernetes c++ 数据库 数据结构 大数据 js 机器学习 微服务 Android Go 程序员 面试 JVM ASP.net core 云原生 人工智能 后端 PHP git CSS golang k8s Nginx Django mybatis 深度学习 多线程 React 架构 devops 爬虫 云计算 Spring Boot LeetCode