没有错误显示时如何调试 JSONDecoder？

Question

我正在构建一个 Swift 应用程序并在 Xcode Playground 中进行测试。调用 NYTimes Search API 并尝试将其响应存储在结构中。代码执行干净，没有出现错误（我正在使用 do、try、catch），但我无法从结果对象中打印任何属性 (print(json.status))。

我的预感是这条线有些可疑，但我不确定是什么，因为从 catch 语句中没有打印错误

let task = URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: { data, response, error in

形成 URL 端点以进行 API 调用：

func APICall() {
        
        let APIKey = "MY_API_KEY_GOES_HERE_BUT_IT'S_A_SECRET"
        let searchTerm = "A Super Bowl Sideshow: See the Ageless Man!"
        
        // Remove the spaces and convert them to percents
        guard let encodedSearchTerm = searchTerm.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed) 
           else {
              print("Error encoding search term in URL")
              return
        }
    
        let url = "https://api.nytimes.com/svc/search/v2/articlesearch.json?q=" + encodedSearchTerm + "&api-key=" + APIKey

        getData(from: url)
}

数据任务：

func getData(from url: String) {
    
    //I believe something is wrong with the following line but I'm not sure what it is
    let task = URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: { data, response, error in
        
        guard let data = data, error == nil else {
            print("Error loading data")
            return
        }
        
        var result: NYTSearchResponse?
        
        do {
            
            result = try JSONDecoder().decode(NYTSearchResponse.self, from: data)
            
        } catch {
            print(error)
        }
        
        guard let json = result else {
            print("Error assigning result to json")
            return
        }
        
        //Try to print these from the resulting object but these commands do not print
        print(json.status)
        print(json.response.docs[0].abstract)
    })
    
    task.resume()
}

我的 NYTSearchResponse 结构，它反映了 NYT API JSON 响应。这很复杂，但我将 json 响应粘贴到 https://app.quicktype.io/ 以构建结构。

// MARK: - Welcome
struct NYTSearchResponse: Codable {
    let status, copyright: String
    let response: Response
}

// MARK: - Response
struct Response: Codable {
    let docs: [Doc]
    let meta: Meta
}

// MARK: - Doc
struct Doc: Codable {
    let abstract: String
    let webURL: String
    let snippet, leadParagraph, printSection, printPage: String
    let source: String
    let multimedia: [Multimedia]
    let headline: Headline
    let keywords: [Keyword]
    let pubDate: Date
    let documentType, newsDesk, sectionName, subsectionName: String
    let byline: Byline
    let typeOfMaterial, id: String
    let wordCount: Int
    let uri: String

    enum CodingKeys: String, CodingKey {
        case abstract
        case webURL = "web_url"
        case snippet
        case leadParagraph = "lead_paragraph"
        case printSection = "print_section"
        case printPage = "print_page"
        case source, multimedia, headline, keywords
        case pubDate = "pub_date"
        case documentType = "document_type"
        case newsDesk = "news_desk"
        case sectionName = "section_name"
        case subsectionName = "subsection_name"
        case byline
        case typeOfMaterial = "type_of_material"
        case id = "_id"
        case wordCount = "word_count"
        case uri
    }
}

// MARK: - Byline
struct Byline: Codable {
    let original: String
    let person: [Person]
    let organization: String?
}

// MARK: - Person
struct Person: Codable {
    let firstname: String
    let middlename: String?
    let lastname: String
    let qualifier, title: String?
    let role, organization: String
    let rank: Int
}

// MARK: - Headline
struct Headline: Codable {
    let main: String
    let kicker, contentKicker: String?
    let printHeadline: String
    let name, seo, sub: String?

    enum CodingKeys: String, CodingKey {
        case main, kicker
        case contentKicker = "content_kicker"
        case printHeadline = "print_headline"
        case name, seo, sub
    }
}

// MARK: - Keyword
struct Keyword: Codable {
    let name, value: String
    let rank: Int
    let major: String
}

// MARK: - Multimedia
struct Multimedia: Codable {
    let rank: Int
    let subtype: String
    let caption, credit: String?
    let type, url: String
    let height, width: Int
    let legacy: Legacy
    let subType, cropName: String

    enum CodingKeys: String, CodingKey {
        case rank, subtype, caption, credit, type, url, height, width, legacy, subType
        case cropName = "crop_name"
    }
}

// MARK: - Legacy
struct Legacy: Codable {
    let xlarge: String?
    let xlargewidth, xlargeheight: Int?
}

// MARK: - Meta
struct Meta: Codable {
    let hits, offset, time: Int
}

Answer 1

我将代码移出操场，它可以工作。