json - 使用可解码协议(protocol)在 Swift 4 中解码 Google 自定义搜索 API-6ren

json - 使用可解码协议(protocol)在 Swift 4 中解码 Google 自定义搜索 API

转载作者：行者123 更新时间：2023-11-30 11:39:58

这是我的 json:

 "metatags": [
         {
          ....

          "og:url": "http://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful",
          "article:author": "https://www.theguardian.com/profile/tomphillips",
          "og:image:height": "720",
          "og:description": "United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’",
          "og:image:width": "1200",
          "og:image": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5",
          "al:ios:url": "gnmguardian://world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful?contenttype=Article&source=applinks",
          "article:publisher": "https://www.facebook.com/theguardian",
          "og:type": "article",
          "al:ios:app_store_id": "409128287",
          "article:section": "World news",
          "article:published_time": "2018-02-27T03:36:30.000Z",
          "og:title": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful",
          "fb:app_id": "180444840287",
          "article:tag": "China,Xi Jinping,Asia Pacific,World news",
          "al:ios:app_name": "The Guardian",
          "og:site_name": "the Guardian",
....
         }
        ]

这是对此API的回应，我想解析出响应中都存在的图像、标题、描述和站点名称。这是到目前为止我创建的数据模型:

struct Metadata: Decodable{
    var metatags: [enclosedTags]

}
    struct enclosedTags: Decodable{
        let image: String
        let title: String
        let description: String
        let siteName: String

        private enum codingKeys : String, CodingKey{
            case image = "og:image", title = "og:title", description = "og:description", siteName = "og:site_name"
        }
    }

@IBAction func onSearch(_ sender: UIButton){

        let session = URLSession.shared


        let datatask = session.dataTask(with: request as URLRequest) { (data, response, error) in
            guard let data = data else {
                print ("Error: Handling URL request")
                return }
            do{
    let tags = try JSONDecoder().decode(Metadata.self, from: data)
                print(tags.metatags)
}
            catch let jerror{
                print("here", jerror)
 }
        }
        datatask.resume()
    }

使用此命令后，我收到以下错误:keyNotFound(Social_Login_api.Metadata.(_7FFB0C3B2CCB4BCEDB9D03985979711B中的CodingKeys).metatags，Swift.DecodingError.Context(codingPath:[]，debugDescription:“没有与关键元标记关联的值(\“元标记\”)。“，underlyingError:nil))

我是否声明了结构错误，或者处理 JSON 请求是否存在问题，任何有用的见解都会很棒。

编辑1:这是请求的整个 JSON 响应，

{
 "kind": "customsearch#search",
 "url": {
  "type": "application/json",
  "template": "https://www.googleapis.com/customsearch/v1?q={searchTerms}&num={count?}&start={startIndex?}&lr={language?}&safe={safe?}&cx={cx?}&sort={sort?}&filter={filter?}&gl={gl?}&cr={cr?}&googlehost={googleHost?}&c2coff={disableCnTwTranslation?}&hq={hq?}&hl={hl?}&siteSearch={siteSearch?}&siteSearchFilter={siteSearchFilter?}&exactTerms={exactTerms?}&excludeTerms={excludeTerms?}&linkSite={linkSite?}&orTerms={orTerms?}&relatedSite={relatedSite?}&dateRestrict={dateRestrict?}&lowRange={lowRange?}&highRange={highRange?}&searchType={searchType}&fileType={fileType?}&rights={rights?}&imgSize={imgSize?}&imgType={imgType?}&imgColorType={imgColorType?}&imgDominantColor={imgDominantColor?}&alt=json"
 },
 "queries": {
  "request": [
   {
    "title": "Google Custom Search - 'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful  United States declines to criticise removal of term limits as liberal  thinkers inside China say move deserves to be 'mocked by civilised countries'     ",
    "totalResults": "4",
    "searchTerms": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful  United States declines to criticise removal of term limits as liberal  thinkers inside China say move deserves to be 'mocked by civilised countries'     ",
    "count": 4,
    "startIndex": 1,
    "inputEncoding": "utf8",
    "outputEncoding": "utf8",
    "safe": "off",
    "cx": "003086370729948886707:yvy2bcavdtu"
   }
  ]
 },
 "context": {
  "title": "*.google"
 },
 "searchInformation": {
  "searchTime": 0.633407,
  "formattedSearchTime": "0.63",
  "totalResults": "4",
  "formattedTotalResults": "4"
 },
 "items": [
  {
   "kind": "customsearch#result",
   "title": "'Ensuring happier lives': Chinese media defends move to make Xi ...",
   "htmlTitle": "&#39;\u003cb\u003eEnsuring happier lives&#39;: Chinese media defends move\u003c/b\u003e to \u003cb\u003emake Xi\u003c/b\u003e ...",
   "link": "https://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful",
   "displayLink": "www.theguardian.com",
   "snippet": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all \npowerful. United States declines to criticise removal of term limits as liberal \nthinkers inside China say move deserves to be 'mocked by civilised countries'. \nTom Phillips in Beijing. Mon 26 Feb 2018 22.36 EST Last modified on Mon 26 \nFeb 2018 ...",
   "htmlSnippet": "&#39;\u003cb\u003eEnsuring happier lives&#39;: Chinese media defends move\u003c/b\u003e to \u003cb\u003emake Xi Jinping all\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003epowerful\u003c/b\u003e. \u003cb\u003eUnited States declines\u003c/b\u003e to \u003cb\u003ecriticise removal\u003c/b\u003e of \u003cb\u003eterm limits\u003c/b\u003e as \u003cb\u003eliberal\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003ethinkers inside China say move deserves\u003c/b\u003e to be &#39;\u003cb\u003emocked\u003c/b\u003e by \u003cb\u003ecivilised countries\u003c/b\u003e&#39;. \u003cbr\u003e\nTom Phillips \u003cb\u003ein\u003c/b\u003e Beijing. Mon 26 Feb 2018 22.36 EST Last modified on Mon 26 \u003cbr\u003e\nFeb 2018&nbsp;...",
   "cacheId": "x54qfhvXmSYJ",
   "formattedUrl": "https://www.theguardian.com/.../ensuring-happier-lives-chinese-media- defends-move-to-make-xi-jinping-all-powerful",
   "htmlFormattedUrl": "https://www.theguardian.com/.../\u003cb\u003eensuring\u003c/b\u003e-\u003cb\u003ehappier\u003c/b\u003e-\u003cb\u003elives\u003c/b\u003e-\u003cb\u003echinese\u003c/b\u003e-\u003cb\u003emedia\u003c/b\u003e- \u003cb\u003edefends\u003c/b\u003e-\u003cb\u003emove-to-make\u003c/b\u003e-\u003cb\u003exi\u003c/b\u003e-\u003cb\u003ejinping\u003c/b\u003e-\u003cb\u003eall\u003c/b\u003e-\u003cb\u003epowerful\u003c/b\u003e",
   "pagemap": {
    "thumbnail": [
     {
      "src": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=620&q=55&auto=format&usm=12&fit=max&s=c857db05131da665271beb49d600180d"
     }
    ],
    "metatags": [
     {
      "format-detection": "telephone=no",
      "handheldfriendly": "True",
      "viewport": "width=device-width,minimum-scale=1,initial-scale=1",
      "apple-mobile-web-app-title": "Guardian",
      "application-name": "The Guardian",
      "msapplication-tilecolor": "#e7edef",
      "theme-color": "#e7edef",
      "msapplication-tileimage": "https://assets.guim.co.uk/images/favicons/77beb32f01ee0157ec193e09e4e18c4e/windows_tile_144_b.png",
      "apple-itunes-app": "app-id=409128287, app-argument=https://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful, affiliate-data=ct=newsmartappbanner&pt=304191",
      "author": "Tom Phillips",
      "thumbnail": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=620&q=55&auto=format&usm=12&fit=max&s=c857db05131da665271beb49d600180d",
      "news_keywords": "China,Xi Jinping,Asia Pacific,World news",
      "og:url": "http://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful",
      "article:author": "https://www.theguardian.com/profile/tomphillips",
      "og:image:height": "720",
      "og:description": "United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’",
      "og:image:width": "1200",
      "og:image": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5",
      "al:ios:url": "gnmguardian://world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful?contenttype=Article&source=applinks",
      "article:publisher": "https://www.facebook.com/theguardian",
      "og:type": "article",
      "al:ios:app_store_id": "409128287",
      "article:section": "World news",
      "article:published_time": "2018-02-27T03:36:30.000Z",
      "og:title": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful",
      "fb:app_id": "180444840287",
      "article:tag": "China,Xi Jinping,Asia Pacific,World news",
      "al:ios:app_name": "The Guardian",
      "og:site_name": "the Guardian",
      "article:modified_time": "2018-02-27T03:37:57.000Z",
      "twitter:app:id:iphone": "409128287",
      "twitter:app:name:googleplay": "The Guardian",
      "twitter:app:name:ipad": "The Guardian",
      "twitter:image": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS90d2l0dGVyX2RlZmF1bHQucG5n&s=84952ae57ce9a937acbeb4ba307a1851",
      "twitter:site": "@guardian",
      "twitter:app:url:ipad": "gnmguardian://world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful?contenttype=Article&source=twitter",
      "twitter:card": "summary_large_image",
      "twitter:app:name:iphone": "The Guardian",
      "twitter:app:id:ipad": "409128287",
      "twitter:app:id:googleplay": "com.guardian",
      "twitter:app:url:googleplay": "guardian://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful",
      "twitter:app:url:iphone": "gnmguardian://world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful?contenttype=Article&source=twitter",
      "twitter:dnt": "on",
      "fb:pages": "10513336322"
     }
    ],
    "newsarticle": [
     {
      "mainentityofpage": "https://www.theguardian.com/world/2018/feb/27/ensuring-happier-lives-chinese-media-defends-move-to-make-xi-jinping-all-powerful",
      "headline": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful",
      "description": "United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’",
      "datepublished": "2018-02-26T22:36:30-0500",
      "datemodified": "2018-02-26T22:37:57-0500",
      "articlebody": "The Communist party’s decision to abolish presidential term limits – a move experts and critics have condemned as a lurch towards unchecked dictatorship in China – is designed to “ensure..."
     }
    ],
    "imageobject": [
     {
      "url": "https://uploads.guim.co.uk/2018/01/31/TheGuardian_AMP.png",
      "width": "190",
      "height": "60"
     },
     {
      "representativeofpage": "true",
      "url": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=700&q=55&auto=format&usm=12&fit=max&s=fe7f74933d50ef2a656efe950160ba56",
      "width": "6835",
      "height": "4101",
      "contenturl": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=300&q=55&auto=format&usm=12&fit=max&s=7b25be283cc4e2d1017f21fa387d7dd5",
      "description": "People walk past a poster of Chinese President Xi Jinping beside a street in Beijing. The Communist party has paved the way for him to assume the presidency indefinitely. Photograph: Greg Baker/AFP..."
     }
    ],
    "person": [
     {
      "sameas": "Tom Phillips",
      "name": "Tom Phillips"
     }
    ],
    "organization": [
     {
      "name": "The Guardian",
      "sameas": "https://www.theguardian.com/"
     }
    ],
    "cse_image": [
     {
      "src": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=300&q=55&auto=format&usm=12&fit=max&s=7b25be283cc4e2d1017f21fa387d7dd5",
      "type": "1",
      "width": "290",
      "height": "174"
     }
    ]
   }
  },
  {
   "kind": "customsearch#result",
   "title": "China: Xi Jinping allowed to rule for ever - Europe Solidaire Sans ...",
   "htmlTitle": "\u003cb\u003eChina\u003c/b\u003e: \u003cb\u003eXi Jinping\u003c/b\u003e allowed to rule for ever - Europe Solidaire Sans ...",
   "link": "https://www.europe-solidaire.org/spip.php?article43289",
   "displayLink": "www.europe-solidaire.org",
   "snippet": "Feb 27, 2018 ... 'Ensuring happier lives': Chinese media defends move to make Xi Jinping all \npowerful. United States declines to criticise removal of term limits as liberal \nthinkers inside China say move deserves to be 'mocked by civilised countries'. \nThe Communist party's decision to abolish presidential term limits – a ...",
   "htmlSnippet": "Feb 27, 2018 \u003cb\u003e...\u003c/b\u003e &#39;\u003cb\u003eEnsuring happier lives\u003c/b\u003e&#39;: \u003cb\u003eChinese media defends move\u003c/b\u003e to \u003cb\u003emake Xi Jinping all\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003epowerful\u003c/b\u003e. \u003cb\u003eUnited States declines\u003c/b\u003e to \u003cb\u003ecriticise removal\u003c/b\u003e of \u003cb\u003eterm limits\u003c/b\u003e as \u003cb\u003eliberal\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003ethinkers inside China say move deserves\u003c/b\u003e to be &#39;\u003cb\u003emocked\u003c/b\u003e by \u003cb\u003ecivilised countries\u003c/b\u003e&#39;. \u003cbr\u003e\nThe Communist party&#39;s decision to abolish presidential \u003cb\u003eterm limits\u003c/b\u003e – a&nbsp;...",
   "cacheId": "xNfA2usjfGwJ",
   "formattedUrl": "https://www.europe-solidaire.org/spip.php?article43289",
   "htmlFormattedUrl": "https://www.europe-solidaire.org/spip.php?article43289",
   "pagemap": {
    "metatags": [
     {
      "viewport": "width=device-width, initial-scale=1.0"
     }
    ],
    "hcard": [
     {
      "fn": "PHILLIPS Tom",
      "url": "https://www.europe-solidaire.org/spip.php?auteur10557",
      "url_text": "PHILLIPS Tom"
     }
    ]
   }
  },
  {
   "kind": "customsearch#result",
   "title": "Xi Jinping | World | The Guardian",
   "htmlTitle": "\u003cb\u003eXi Jinping\u003c/b\u003e | World | The Guardian",
   "link": "https://www.theguardian.com/world/xi-jinping",
   "displayLink": "www.theguardian.com",
   "snippet": "1 day ago ... 'Ensuring happier lives': Chinese media defends move to make Xi Jinping all \npowerful. United States declines to criticise removal of term limits as liberal \nthinkers inside China say move deserves to be 'mocked by civilised countries'. \nPublished: 10:36 PM. 'Ensuring happier lives': Chinese media defends ...",
   "htmlSnippet": "1 day ago \u003cb\u003e...\u003c/b\u003e &#39;\u003cb\u003eEnsuring happier lives&#39;: Chinese media defends move\u003c/b\u003e to \u003cb\u003emake Xi Jinping all\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003epowerful\u003c/b\u003e. \u003cb\u003eUnited States declines\u003c/b\u003e to \u003cb\u003ecriticise removal\u003c/b\u003e of \u003cb\u003eterm limits\u003c/b\u003e as \u003cb\u003eliberal\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003ethinkers inside China say move deserves\u003c/b\u003e to be &#39;\u003cb\u003emocked\u003c/b\u003e by \u003cb\u003ecivilised countries\u003c/b\u003e&#39;. \u003cbr\u003e\nPublished: 10:36 PM. &#39;\u003cb\u003eEnsuring happier lives&#39;: Chinese media defends\u003c/b\u003e&nbsp;...",
   "cacheId": "UjbuXbyQHKsJ",
   "formattedUrl": "https://www.theguardian.com/world/xi-jinping",
   "htmlFormattedUrl": "https://www.theguardian.com/world/\u003cb\u003exi\u003c/b\u003e-\u003cb\u003ejinping\u003c/b\u003e",
   "pagemap": {
    "cse_thumbnail": [
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      "width": "290",
      "height": "174",
      "src": "https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcToDkj5l17V62vsyZ0lkbCiH6Er9PEydDqKzxA7yPuOB5irCw3rceke9ks"
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    "metatags": [
     {
      "format-detection": "telephone=no",
      "handheldfriendly": "True",
      "viewport": "width=device-width,minimum-scale=1,initial-scale=1",
      "apple-mobile-web-app-title": "Guardian",
      "application-name": "The Guardian",
      "msapplication-tilecolor": "#e7edef",
      "theme-color": "#e7edef",
      "msapplication-tileimage": "https://assets.guim.co.uk/images/favicons/77beb32f01ee0157ec193e09e4e18c4e/windows_tile_144_b.png",
      "apple-itunes-app": "app-id=409128287, app-argument=https://www.theguardian.com/world/xi-jinping, affiliate-data=ct=newsmartappbanner&pt=304191",
      "og:url": "http://www.theguardian.com/world/xi-jinping",
      "al:ios:url": "gnmguardian://world/xi-jinping?contenttype=list&source=applinks",
      "og:type": "website",
      "al:ios:app_store_id": "409128287",
      "fb:app_id": "180444840287",
      "al:ios:app_name": "The Guardian",
      "og:site_name": "the Guardian",
      "twitter:app:id:iphone": "409128287",
      "twitter:app:name:googleplay": "The Guardian",
      "twitter:app:name:ipad": "The Guardian",
      "twitter:site": "@guardian",
      "twitter:app:url:ipad": "gnmguardian://world/xi-jinping?contenttype=list&source=twitter",
      "twitter:card": "summary",
      "twitter:app:name:iphone": "The Guardian",
      "twitter:app:id:ipad": "409128287",
      "twitter:app:id:googleplay": "com.guardian",
      "twitter:app:url:iphone": "gnmguardian://world/xi-jinping?contenttype=list&source=twitter",
      "twitter:dnt": "on",
      "fb:pages": "10513336322",
      "twitter:url": "https://www.theguardian.com/world/xi-jinping",
      "og:title": "Xi Jinping | World news | The Guardian"
     }
    ],
    "webpage": [
     {
      "keywords": "Asia Pacific"
     }
    ],
    "cse_image": [
     {
      "src": "https://i.guim.co.uk/img/media/07a39d19a47e2e87502cd64d2ea09cd841d59a4a/591_660_4794_2876/master/4794.jpg?w=300&q=55&auto=format&usm=12&fit=max&s=ea982bfe9f0599c02e30198d63d0a1a8"
     }
    ]
   }
  },
  {
   "kind": "customsearch#result",
   "title": "مارس 2015 – علوم انسانی olomeensani.com",
   "htmlTitle": "مارس 2015 – علوم انسانی olomeensani.com",
   "link": "http://olomeensani.com/2015/03",
   "displayLink": "olomeensani.com",
   "snippet": "30 مارس 2015 ... Kate Lamb in Jakarta; 'Ensuring happier lives': Chinese media defends move to \nmake Xi Jinping all powerful فوریه 27, 2018. United States declines to criticise \nremoval of term limits as liberal thinkers inside China say move deserves to be '\nmocked by civilised countries'The Communist party's decision to ...",
   "htmlSnippet": "30 مارس 2015 \u003cb\u003e...\u003c/b\u003e Kate Lamb \u003cb\u003ein\u003c/b\u003e Jakarta; &#39;\u003cb\u003eEnsuring happier lives\u003c/b\u003e&#39;: \u003cb\u003eChinese media defends move\u003c/b\u003e to \u003cbr\u003e\n\u003cb\u003emake Xi Jinping all powerful\u003c/b\u003e فوریه 27, 2018. \u003cb\u003eUnited States declines\u003c/b\u003e to \u003cb\u003ecriticise\u003c/b\u003e \u003cbr\u003e\n\u003cb\u003eremoval\u003c/b\u003e of \u003cb\u003eterm limits\u003c/b\u003e as \u003cb\u003eliberal thinkers inside China say move deserves\u003c/b\u003e to be &#39;\u003cbr\u003e\n\u003cb\u003emocked\u003c/b\u003e by \u003cb\u003ecivilised countries\u003c/b\u003e&#39;The Communist party&#39;s decision to&nbsp;...",
   "cacheId": "j9CqlbDCdQAJ",
   "formattedUrl": "olomeensani.com/2015/03",
   "htmlFormattedUrl": "olomeensani.com/2015/03",
   "pagemap": {
    "metatags": [
     {
      "viewport": "width=device-width, initial-scale=1",
      "msapplication-tileimage": "http://olomeensani.com/wp-content/uploads/2015/12/cropped-DSC_0187.JPG-e1449088658125-1-270x270.jpg"
     }
    ]
   }
  }
 ]
}

最终编辑:

您先生让我很高兴，很高兴看到这个结果，

Optional([Social_Login_api.Item(metatags: Optional([Social_Login_api.enclosedTags(image: Optional("https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5"), title: Optional("\'Ensuring happier lives\': Chinese media defends move to make Xi Jinping all powerful"), description: Optional("United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’"), siteName: Optional("the Guardian"))]))

最后您能否指出如何在 json 提取字符串之前摆脱这些烦人的可选措辞？

最佳答案

在代码中，

struct Metadata: Decodable
{
    var metatags: [enclosedTags]?
}

struct enclosedTags: Decodable
{
    let image: String?
    let title: String?
    let description: String?
    let siteName: String?

    private enum CodingKeys : String, CodingKey
    {
        case image = "og:image", title = "og:title", description = "og:description", siteName = "og:site_name"
    }
}

它必须是 CodingKeys 而不是 codingKeys。它是“C”而不是“c”
此外，可编码类型的属性，即Metadata和enheldTags必须是可选。您不知道将从 API 中得到什么。如果属性不是可选的，并且您没有从 API 获取任何一个键，则完整的对象将为 nil。

编辑:

使用尝试？而不是尝试

let tags = try? JSONDecoder().decode(Metadata.self, from: data)
print(tags?.metatags)

预期的 JSON 格式:

      {
        "metatags": [
                 {
                  "og:description": "United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’",
                  "og:image": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5",
                  "og:title": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful",
                 }
                ]
      }

示例代码:

    let jsonString = """
    {
    "metatags": [
             {
              "og:description": "United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’",
              "og:image": "https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5",
              "og:title": "'Ensuring happier lives': Chinese media defends move to make Xi Jinping all powerful",
             }
            ]
        }
    """

    if let jsonData = jsonString.data(using: .utf8)
    {
        let obj = try? JSONDecoder().decode(Metadata.self, from: jsonData)
        print(obj?.metatags)
    }

输出:

[SampleNavigation.ViewController.enclosedTags(image: Optional("https://i.guim.co.uk/img/media/5d33d9276cf4388564b5bf4d42e0cd4ad8ec221e/0_230_6835_4101/master/6835.jpg?w=1200&h=630&q=55&auto=format&usm=12&fit=crop&crop=faces%2Centropy&bm=normal&ba=bottom%2Cleft&blend64=aHR0cHM6Ly91cGxvYWRzLmd1aW0uY28udWsvMjAxOC8wMS8zMS9mYWNlYm9va19kZWZhdWx0LnBuZw&s=391c7c897cafc35a55dd29b48ed544d5"), title: Optional("\'Ensuring happier lives\': Chinese media defends move to make Xi Jinping all powerful"), description: Optional("United States declines to criticise removal of term limits as liberal thinkers inside China say move deserves to be ‘mocked by civilised countries’"), siteName: nil)]

编辑2:

struct Response: Decodable
{
    var items: [Item]?
}

struct Item: Decodable
{
    var pagemap: Pagemap?
}

struct Pagemap: Decodable
{
    var metatags: [enclosedTags]?
}

struct enclosedTags: Decodable
{
    let image: String?
    let title: String?
    let description: String?
    let siteName: String?

    private enum CodingKeys : String, CodingKey
    {
        case image = "og:image", title = "og:title", description = "og:description", siteName = "og:site_name"
    }
}

解码 JSON:

    if let jsonData = jsonString.data(using: .utf8)
    {
        let obj = try? JSONDecoder().decode(Response.self, from: jsonData)
        print(obj?.items)
    }

编辑3:

您可以使用容器来提取嵌套信息，而不是为pagemap创建单独的结构，即您可以使用以下 结构，

struct Response: Decodable
{
    var items: [Item]?
}

struct Item: Decodable
{
    var metatags: [enclosedTags]?

    enum CodingKeys : String, CodingKey
    {
        case pagemap
    }

    enum PageMapKeys: String, CodingKey
    {
        case metatags
    }

    init(from decoder: Decoder) throws
    {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        let pagemap = try values.nestedContainer(keyedBy: PageMapKeys.self, forKey: .pagemap)
        metatags = try pagemap.decode([enclosedTags].self, forKey: .metatags)
    }
}

struct enclosedTags: Decodable
{
    let image: String?
    let title: String?
    let description: String?
    let siteName: String?

    private enum CodingKeys : String, CodingKey
    {
        case image = "og:image", title = "og:title", description = "og:description", siteName = "og:site_name"
    }
}

如果您仍然遇到任何问题，请告诉我。快乐编码..🙂

关于json - 使用可解码协议(protocol)在 Swift 4 中解码 Google 自定义搜索 API，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49358645/

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json - 使用可解码协议(protocol)在 Swift 4 中解码 Google 自定义搜索 API