为什么代码没有在tableview中发布JSON信息

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如何解决为什么代码没有在tableview中发布JSON信息？

您好，我是编程初学者，我按照在线教程从 Json 文件中解析信息。为了获取 URL 链接，我创建了一个包含 Json 文件的本地服务器。当我启动程序时出现错误。

Called Thread 2: signal SIGABRT for the code snippet            
let Json = try JsONserialization.JsonObject(with: data!,options: .mutableContainers) as! [String: AnyObject]

Google 说有一个未连接的插座，但我的代码中的插座已连接。

还有多个错误警告，Google说数组有问题，我必须将其设置为NSDictionary，但我从未将任何变量声明为数组或字典。

Could not cast value of type '__NSArraym' (0x7fff80919120) to 'NSDictionary' (0x7fff809193b0).
2021-06-30 22:01:07.257592+0200 Booknerd3.0[71572:3475394] Could not cast value of type '__NSArraym' (0x7fff80919120) to 'NSDictionary' (0x7fff809193b0).
Could not cast value of type '__NSArraym' (0x7fff80919120) to 'NSDictionary' (0x7fff809193b0).
CoreSimulator 757.5 - Device: iPhone 8 (A2400EB4-8BA3-4297-9DF3-1743AA0BB7E4) - Runtime: iOS 14.5 (18E182) - DeviCEType: iPhone 8

Json 文件：

{
    "books":
    [
        {
            "author": "Chinua Achebe","country": "Nigeria","imagelink": "https://s3.amazonaws.com/AKIAJC5RLADLUMVRPFDQ.book-thumb-images/ableson.jpg","language": "English","link": "https://en.wikipedia.org/wiki/Things_Fall_Apart\n","pages": 209,"title": "Things fall Apart","year": 1958
        },{
            "author": "Hans Christian Andersen","country": "Denmark","imagelink": "https://s3.amazonaws.com/AKIAJC5RLADLUMVRPFDQ.book-thumb-images/ableson2.jpg","language": "Danish","link": "https://en.wikipedia.org/wiki/Fairy_Tales_Told_for_Children._First_Collection.\n","pages": 784,"title": "Fairy tales","year": 1836
        }
    ]
}

我的视图控制器

import UIKit

class MainScreenVIEwController: UIVIEwController,UItableVIEwDelegate,UItableVIEwDatasource {

    @IBOutlet weak var tablevIEw: UItableVIEw!
    
    var books: [Books]? = []
    
    overrIDe func vIEwDIDLoad() {
        super.vIEwDIDLoad()
        
        fetchArticle()
        
    }
    
    func fetchArticle(){
        let urlrequest = URLrequest(url: URL(String: "http://localhost:3000/books")!)
        
        let task = URLSession.shared.dataTask(with: urlrequest) {  (data,response,error) in

            if error != nil {
                print(error)
                return
            }
            self.books = [Books]()
            do {
                let Json = try JsONserialization.JsonObject(with: data!,options: .mutableContainers) as! [String: AnyObject]

                if let booksFromJson = Json["books"] as? [[String : AnyObject]]{
                    for bookFromJson in booksFromJson {
                        let book = Books()
                        if let title = bookFromJson["title"] as? String,let author = bookFromJson["author"] as? String,let imagelink = bookFromJson["imagelink"] as? String {

                            book.author = author
                            book.title = title
                            book.imagelink = imagelink
                        }
                        self.books?.append(book)
                    }
                }
                dispatchQueue.main.async {
                    self.tablevIEw.reloadData()
                }

                } catch let error {
                    print(error)
                }
            }
            task.resume()
        }


        func tableVIEw(_ tableVIEw: UItableVIEw,cellForRowAt indexPath: IndexPath) -> UItableVIEwCell {
            let cell = tableVIEw.dequeueReusableCell(withIDentifIEr: "bookCell",for: indexPath) as! BookCell
            
            cell.title.text = self.books?[indexPath.item].title
            cell.author.text = self.books?[indexPath.item].author

            return cell
        }
        
        func tableVIEw(_ tableVIEw: UItableVIEw,numberOfRowsInSection section: int) -> Int {
            return self.books?.count ?? 0
        }

        func numberOfSections(in tableVIEw: UItableVIEw) -> Int {
            return 1
        }
    }
}

解决方法

if let booksFromJson = json["books"] as? [[String : AnyObject]]...

[String:Any]

[String:[String: Any]]

struct BooksResponse: Decodable {
    let books: [Book]
}

struct Book: Decodable {
    let author: String
    let imageLink: URL
    let title: String
}

// This part declared somewhere
enum JsonBooksDecodingError: Error {
    case dataCorrupted
}
// -- 

func fetchArticle() {
    guard  let urlrequest = URLrequest(url: URL(String: "http://localhost:3000/books")) else {
        assert(false,"URL broken")
    }

    URLSession.shared.dataTask(with: urlrequest) {  (data,response,error) in

        if error != nil {
            print(error)
            return
        }

        do {
            let booksResponse = try handle(booksData: data)
            self.books = booksResponse.books
            
            DispatchQueue.main.async {
                self.tableview.reloadData()
            }
        }

        } catch let error {
            print(error)
        }
    }
    .resume()
}   

func handle(booksData data: Data) throws -> BooksResponse {
    guard let jsonData = jsonData else {
        throw JsonBooksDecodingError.dataCorrupted
    }

    return try JSONDecoder().decode(BooksResponse.self,from: jsonData)
}

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