Ios JSON解析-->；无法强制转换类型为'__NSCFString'；（0x1e5c38f90）至'；NSDictionary'；（0x1e5c39bc0）

我以字符串格式获取上面的json数据，并使用

JSONSerialization

进行解析，就像下面的方法一样。我可以在控制台中打印值数据，但如何基于键访问内部值

{"msgType":"UPDATE_S","macAddress":"2F-01-01-01-01-01","deviceName":"vMining","deviceType":"vSensor","groupId":"vMiningYo","param”:”truckDetail","value":"[{'TruckNo':1,'Status':'Moving to crusher','Speed':0,'CheckPointNumber':16,'CurrentLoad':346,'TirePressureIssueWheelNumber':0,'TirePressure':6,'Longitude':36.835072,'Latitude':-109.059769,'Altitude':1.0}]","valueDimension":"JSON","topic":"in/vMiningYo_ios/vMINING","_MessageGateway_TimeMilliseconds":1557471205646,"_MessageGateway_TimeSeconds":1557471205,"_MessageGateway_TimeISO8601":"2019-05-10T06:53:25.646Z","_MessageGateway_MessageClientType":"WS","_MessageGateway_Topic":"in/vMiningYo_ios/vMINING"}

在控制台中打印：

    func recieveMessage(json:String){
    guard let data = json.data(using: .utf16),
        let jsonData = try? JSONSerialization.jsonObject(with: data),
        let jsonDict = jsonData as? [String: Any],
        let param = jsonDict["param"] as? String else {
            return
    }
    if param == "truckDetail"{
        print("VALUE:: \(jsonDict["value"]!)")
        let truckData = jsonDict["value"]! as! [String:Any]
        print(truckData)
        print(truckData["Status"])
        //            if let truckData = jsonDict["value"] as? [String: Any]{
        //                print(truckData)
        //            }
    }
}

如何打印此词典中的状态值？提前感谢。

jsonDict[“value”]

是一个json字符串，而不是字典

VALUE:: [{'TruckNo':1,'Status':'Moving to crusher','Speed':0,'CheckPointNumber':16,'CurrentLoad':346,'TirePressureIssueWheelNumber':0,'TirePressure':6,'Longitude':36.835072,'Latitude':-109.059769,'Altitude':1.0}]

---

有两个主要问题：

key

value

的对象是一个

字符串（显然是JSON）。错误清楚地表明了这一点

但实际上它不是有效的JSON，因为JSON字符串必须用双引号包装，不支持单引号

您需要另外两个步骤：用双引号替换单引号，并分别反序列化JSON字符串

对象是一个数组。使用循环或按索引获取项

let truckStr = jsonDict["value"] as! String
let jsonDic = try! JSONSerialization.jsonObject(with:Data(truckStr.utf8)) as! [String: Any] 
print(jsonDic["Status"])

---

重复的。@wings基于此答案，我无法按要求进行更改。您能建议我如何修复它吗？保留代码后，我遇到此异常，我如何在此处修复-->线程1：致命错误：“重试！”表达式意外引发错误：error Domain=NSCOCAERRORDOMAIN Code=3840“字符1周围的对象中的值没有字符串键。”UserInfo={NSDEBUGSCRIPTION=字符1周围的对象中的值没有字符串键。}

let json = """
{"msgType":"UPDATE_S","macAddress":"2F-01-01-01-01-01","deviceName":"vMining","deviceType":"vSensor","groupId":"vMiningYo","param":"truckDetail","value":"[{'TruckNo':1,'Status':'Moving to crusher','Speed':0,'CheckPointNumber':16,'CurrentLoad':346,'TirePressureIssueWheelNumber':0,'TirePressure':6,'Longitude':36.835072,'Latitude':-109.059769,'Altitude':1.0}]","valueDimension":"JSON","topic":"in/vMiningYo_ios/vMINING","_MessageGateway_TimeMilliseconds":1557471205646,"_MessageGateway_TimeSeconds":1557471205,"_MessageGateway_TimeISO8601":"2019-05-10T06:53:25.646Z","_MessageGateway_MessageClientType":"WS","_MessageGateway_Topic":"in/vMiningYo_ios/vMINING"}
"""

let data = Data(json.utf8)
do {
    if let result = try JSONSerialization.jsonObject(with: data) as? [String:Any],
       let param = result["param"] as? String {
       if param == "truckDetail" {
           let value = result["value"] as! String
           let valueString = value.replacingOccurrences(of: "\'", with: "\"")
           let valueData = Data(valueString.utf8)
           if let valueResult = try JSONSerialization.jsonObject(with: valueData) as? [[String:Any]] {
              for item in valueResult {
                   print(item["Status"] as? String ?? "n/a")
              }
           }
       }
    }
} catch { print(error)}