如何在Swift3中获取Json包的内容(unwrap Json package)

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我想在这个帖子里面总结两个问题:一个是通过ReST获取Json的语句,这个比较简单

另一个是如何将Json包一层一层转存为字典,并最终通过keyword: String获得所需内容方法

废话不说,来看代码

首先是服务器返回的Json形式,这里以youtube API为例,因为google做的Json包很规范(都是 String: String 或者 String: Int)

youtube API 的 请求 URL 形式(我这里仅获取关键字搜索视频列表)是

https://www.googleapis.com/youtube/v3/search?part=snippet&q=视频关键字&type=video&key=你的API Key

其中,视频关键字比如 minecraft

API Key 形如AIzaSyDDqTGpVR7jxeozoOEjH6SLaRdw0YY-HPQ

其返回的Json包形式为

{
 "kind": "youtube#searchListResponse","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/dJyYeiv8CbvQiayof_7MqRQOSi8\"","nextPageToken": "CAUQAA","regionCode": "AU","pageInfo": {
  "totalResults": 1000000,"resultsPerPage": 5
 },"items": [
  {
   "kind": "youtube#searchResult","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/ey6kUbVRRdmcLIPpklkbtxDp_-o\"","id": {
    "kind": "youtube#video","videoId": "XgdgO5UzdR4"
   },"snippet": {
    "publishedAt": "2016-11-27T12:00:01.000Z","channelId": "UCUVa51UA_690sEKyRbHb-5A","title": "5 Werewolves Caught on Camera & Spotted In Real Life!","description": "5 Werewolves Caught on Tape & Spotted In Real Life! Description: Myths and stories of humans with the ability to transform into animals exist across all human ...","thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/XgdgO5UzdR4/default.jpg","width": 120,"height": 90
     },"medium": {
      "url": "https://i.ytimg.com/vi/XgdgO5UzdR4/mqdefault.jpg","width": 320,"height": 180
     },"high": {
      "url": "https://i.ytimg.com/vi/XgdgO5UzdR4/hqdefault.jpg","width": 480,"height": 360
     }
    },"channelTitle": "Top 5s Finest","liveBroadcastContent": "none"
   }
  },{
   "kind": "youtube#searchResult","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/LKJrjJEelN2h1v58M533Dwv_fjs\"","videoId": "KUS0454UUDM"
   },"snippet": {
    "publishedAt": "2016-08-03T10:16:33.000Z","channelId": "UC0rzsIrAxF4kCsALP6J2EsA","title": "MAIN-MAIN: WEREWOLF","description": "Yang mau liat tutorial cara mainnya,klik di sini: https://youtu.be/ShGULqRjLMk.","thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/KUS0454UUDM/default.jpg","medium": {
      "url": "https://i.ytimg.com/vi/KUS0454UUDM/mqdefault.jpg","high": {
      "url": "https://i.ytimg.com/vi/KUS0454UUDM/hqdefault.jpg","channelTitle": "Raditya Dika","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/8qIl76CAeB__wn-Sd_g4pik1XT0\"","videoId": "fScsIQ8wgNo"
   },"snippet": {
    "publishedAt": "2016-10-02T22:21:35.000Z","channelId": "UCNUohh38MTkgY4xKpFeVGmQ","title": "Werewolf Scenes - My Favorite Transformation HD","description": "Werewolf Scenes - My Favorite Transformation HD.","thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/fScsIQ8wgNo/default.jpg","medium": {
      "url": "https://i.ytimg.com/vi/fScsIQ8wgNo/mqdefault.jpg","high": {
      "url": "https://i.ytimg.com/vi/fScsIQ8wgNo/hqdefault.jpg","channelTitle": "ENJOY PLEASE","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/SByO_v4iInfFZ5GUe2xJUYXIWh4\"","videoId": "ShGULqRjLMk"
   },"snippet": {
    "publishedAt": "2016-08-03T10:13:33.000Z","title": "TUTORIAL: MAIN WEREWOLF","description": "Ini adalah video tutorial untuk main werewolf. Untuk melihat video permainannya,bisa klik di sini: https://youtu.be/KUS0454UUDM.","thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/ShGULqRjLMk/default.jpg","medium": {
      "url": "https://i.ytimg.com/vi/ShGULqRjLMk/mqdefault.jpg","high": {
      "url": "https://i.ytimg.com/vi/ShGULqRjLMk/hqdefault.jpg","etag": "\"uQc-MPTsstrHkQcRXL3IWLmeNsM/NjscIZ4D3C-FDPsnBKe-j5tslrE\"","videoId": "MI1Yi2AUVAc"
   },"snippet": {
    "publishedAt": "2016-09-09T07:27:23.000Z","title": "Vampire vs Werewolf Fight Scene HD - Van Helsing - Vampire vs Lycan Wolf","description": "Vampire vs Werewolf Fight Scene HD - Van Helsing - Vampire vs Lycan Wolf.","thumbnails": {
     "default": {
      "url": "https://i.ytimg.com/vi/MI1Yi2AUVAc/default.jpg","medium": {
      "url": "https://i.ytimg.com/vi/MI1Yi2AUVAc/mqdefault.jpg","high": {
      "url": "https://i.ytimg.com/vi/MI1Yi2AUVAc/hqdefault.jpg","liveBroadcastContent": "none"
   }
  }
 ]
}
---------------------------------------------------------------------------------------------------------------------
第 0 层
{}
第一层
{
"kind":"youtube#searchListResponse",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/g4lxZZLl2WXJPiISOtol-Vf33d8\"",
"nextPageToken":"CAUQAA",
"regionCode":"US",
"pageInfo":{},
"items":[]
}

第二层
对于 pageInfo
{
"totalResults":1000000,
"resultsPerPage":5
}

对于 items (注意那个中括号)
[[
{
"kind":"youtube#searchResult",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/ey6kUbVRRdmcLIPpklkbtxDp_-o\"",
"id":{},
"snippet":{}
},
{
"kind":"youtube#searchResult",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/LKJrjJEelN2h1v58M533Dwv_fjs\"",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/8qIl76CAeB__wn-Sd_g4pik1XT0\"",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/SByO_v4iInfFZ5GUe2xJUYXIWh4\"",
"etag":"\"uQc-MPTsstrHkQcRXL3IWLmeNsM/NjscIZ4D3C-FDPsnBKe-j5tslrE\"",
"snippet":{}
}
]
这就是说,中括号里面的内容实际上是一个数组,这个数组有五个元素。

第三层
以其中一个元素为例
对于 id
{
"kind":"youtube#video",
"videoId":"XgdgO5UzdR4"
}
对于 snippet
{
"publishedAt":"2016-11-27T12:00:01.000Z",
"channelId":"UCUVa51UA_690sEKyRbHb-5A",
"title":"5WerewolvesCaughtonCamera&SpottedInRealLife!",
"description":"5WerewolvesCaughtonTape&SpottedInRealLife!Description:Mythsandstoriesofhumanswiththeabilitytotransformintoanimalsexistacrossallhuman...",
"thumbnails":{},
"channelTitle":"Top5sFinest",
"liveBroadcastContent":"none"
}
第四层
对于 thumbnails
{
"default":{},
"medium":{},
"high":{}
}
第五层
对于 default
{
"url":"https://i.ytimg.com/vi/XgdgO5UzdR4/default.jpg",
"width":120,
"height":90
}
其它两个类似

至此Json 包解析完毕。
然后附上代码。首先是ReST请求部分
然后是Json解析部分
只解释Json解析部分。我现在的目的是取出四个key值:视频的title、description、thumbnail default url 还有 videoId过程是这样:根据我上面的分析,从第一层开始(第 0 层不算)每层都建立[String: AnyObject]字典或数组(根据Json那一层的结构而定)。在最后一层只有String内容的时候,也可以建立[String: String]字典(也就是idDict也可以建成[String: String]的,别的不可以。)第一层 - resultDict 这个不能建成[String: String],因为pageInfo和items关键字对应的不是String,而是一个或多个子字典。第二层 - 因为pageInfo里面的内容我不需要(如需要建字典),所以只有items对应的数组 -- itemsArray  (建数组因为items本身是五个元素组成的数组,在前面已经说明。)第三层 - 对于 id -- idDict字典,这个可以建[String: AnyObject]也可以建[String: String](因为内容只有String,建AnyObject的话,就需要cast一下(as! String)。)对于 snippet -- snippetDict字典,这个必须[String: AnyObject]第四层 - thumbnailDict第五层 - defaultDict,其它两个Key里面的信息不需要,如果需要,也可以建相应字典提取出来。然后我建了一个每个元素都是[String: AnyObject]字典的Array,形如[[String: AnyObject]],用来储存我提取出来的四个keyword对应的信息。当然,这个数组建成[[String: String]]也是可以的。当时对这个代码理解还不深,属于半迷糊状态。然后就大功告成。
原文链接:https://www.f2er.com/swift/322176.html

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