json - 在 swift 4 中从 json 加载数据的空 tableview

Question

所以是的，谢谢你们，我刚刚将整个代码更改为可编码为正确的 swift 4 哈哈。但控制台上仍然没有显示表格 View : “已下载 下载时出现问题”

final let url = URL(string: "https://newsapi.org/v2/top-headlines?sources=espn&apiKey=ada86a1d56d348a29a7c7501869bac2f")
private var articles = [Article]()
@IBOutlet weak var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()
        downloadJson()
        tableView.tableFooterView = UIView()
    }

func downloadJson(){
            guard let downloadURL = url else {return}
            URLSession.shared.dataTask(with: downloadURL){data, URLResponse, error in
                guard let data = data, error == nil, URLResponse != nil else{
                    print("something is wrong")
                    return
                }
                print("downloaded")
                do
                {
                    let decoder = JSONDecoder()
                    let downloadedArticles = try decoder.decode(Articles.self, from: data)
                    self.articles = downloadedArticles.articles
                    DispatchQueue.main.async {
                        self.tableView.reloadData()
                    }
                }catch {
                    print("something is wrong when downloaded")
                }
            }.resume()
        }

这是来自文章可编码类

class Articles: Codable {
    let articles: [Article]

    init(articles: [Article]){
        self.articles = articles
    }
}

class Article: Codable{
    let title: String
    let description: String
    let author: String
    let image: String

    init(title: String, description: String, author: String, image: String){
        self.title = title
        self.description = description
        self.author = author
        self.image = image
        }
}

这是 cellforrowat(我无法发布它，因为我的整个帖子主要是代码。哈哈):

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "ArticleCell") as? ArticleCell else {
            return UITableViewCell()}
        cell.titleLabel.text = "" + articles[indexPath.row].title
        cell.descLabel.text = "" + articles[indexPath.row].description
        cell.authorLabel.text = "" + articles[indexPath.row].author

        if let imageURL = URL(string: articles[indexPath.row].image){
            DispatchQueue.global().async {
                let data = try? Data(contentsOf: imageURL)
                if let data = data {
                    let image = UIImage(data: data)
                    DispatchQueue.main.async {
                        cell.imgView.image = image
                    }
                }
            }
        }
        return cell
    }

Answer 1

您应该使用 json 和articlesFromJs 检查调试内容。 可能articleFromJs为空或者JSON格式不正确。

let json = try JSONSerialization.jsonObject(with: data!, options: .mutableContainers) as! [String : AnyObject]

和

if let articlesFromJson = json["articles"] as? [[String : >AnyObject]]

还使用 Codable 而不是 JSONSerialization。