从 JSON 获取多个字符串

问题描述

所以 JSON 变量 let json = JSON(nearbyChargingSites.jsonString!) 包含当前数据。：

{
  "timestamp" : 1626902257093,"superchargers" : [
    {
      "location" : {
        "lat" : 63.325319,"long" : 10.305137
      },"total_stalls" : 19,"distance_miles" : 10.064082000000001,"type" : "supercharger","site_closed" : false,"available_stalls" : 15,"name" : "Leinstrand,norway - Klett"
    },{
      "location" : {
        "lat" : 63.466445999999998,"long" : 10.91766
      },"total_stalls" : 16,"distance_miles" : 11.838984999999999,"available_stalls" : 16,"name" : "Stjørdal,norway"
    },{
      "location" : {
        "lat" : 63.734355000000001,"long" : 11.281487
      },"total_stalls" : 12,"distance_miles" : 31.206503999999999,"available_stalls" : 11,"name" : "Levanger,{
      "location" : {
        "lat" : 62.832030000000003,"long" : 10.009639999999999
      },"total_stalls" : 20,"distance_miles" : 44.117753,"available_stalls" : 17,"name" : "Berkåk,norway"
    }
  ],"congestion_sync_time_utc_secs" : 1626902199,"destination_charging" : [
    {
      "distance_miles" : 23.366278999999999,"name" : "Bårdshaug Herregård","location" : {
        "lat" : 63.299208,"long" : 9.8448650000000004
      },"type" : "destination"
    },{
      "distance_miles" : 38.390034,"name" : "Fosen Fjordhotel","location" : {
        "lat" : 63.959356999999997,"long" : 10.223908
      },{
      "distance_miles" : 46.220022999999998,"name" : "Falksenteret","location" : {
        "lat" : 63.293301999999997,"long" : 9.0834460000000004
      },{
      "distance_miles" : 54.981445000000001,"name" : "Væktarstua","location" : {
        "lat" : 62.908683000000003,"long" : 11.893306000000001
      },"type" : "destination"
    }
  ]
}

我使用 SwiftyJSON 并尝试获取增压器的纬度、经度和名称，如下所示：

let jsonName = json["superchargers"]["name"]
let jsonLat = json["superchargers"]["location"]["lat"]
let jsonLong = json["superchargers"]["location"]["long"]
            

尝试打印其中任何一个时，所有这些都返回 nil。

任何想法我做错了什么，以及如何做到这一点？

我想这样做的原因是我想将它们作为 annotation 添加到 MKMapView。

解决方法

第一个错误是您使用的 JSON 初始值设定项将创建单个 JSON 字符串对象，它不会将字符串解析为 JSON 数据：

代替：

let json = JSON(nearbyChargingSites.jsonString!)

您需要使用：

let json = JSON(data: dataFromJSONString)

其次，您需要遍历 superchargers 数组以收集所有值

尝试类似：

    if let dataFromString = nearbyChargingSites.jsonString!.data(using: .utf8,allowLossyConversion: false) {
        let json = try! JSON(data: dataFromString,options: .allowFragments)

        for supercharger in json["superchargers"].arrayValue {
            let jsonName = supercharger["name"].stringValue
            let jsonLat = supercharger["location"]["lat"].doubleValue
            let jsonLong = supercharger["location"]["long"].doubleValue
        }
    }

请注意，上面的代码不会执行错误处理，如果 JSON 中缺少值，则会崩溃。