json not parsing properly

Question

So I tried to parse a json file and when I parse it as per the syntax, it gives me an error that cannot change the string to an array of dictionary, but when I fix the problem, it generates nil. Can anyone give an opinion

func jsonFour() {
    let string = "[{\"address\": 7023000630,\"reportStatus\": \"Retrieved\",\"currentLocation\": {\"latitude\": 29.8529, \"longitude\": 73.99332,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\"} }, {\"address\": 7290098339, \"reportStatus\": \"Retrieved\", \"currentLocation\": {\"latitude\": 21.628569, \"longitude\": 72.996956,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\" } } ]"

    let data = string.data(using: .utf8)!
    do {
        if let jsonArray = try JSONSerialization.jsonObject(with: data, options : JSONSerialization.ReadingOptions.mutableContainers) as? [[ String : Any ]]
        {
            print(jsonArray) // use the json here
            let address = jsonArray["address"] as! [[String:Any]]
            if let timestamp = address["timestamp"] as? [String]{print(timestamp)}
        } else {
            print("bad json")
        }
    } catch let error as NSError {
        print(error)
    }

}

When I remove the double brackets from "String : Any", it runs fine, but does not give any value but nil.

And when I proceed with this way, it skips the if statement and just prints "bad json".

What am I doing wrong here?

score 2 · Answer 1 · answered Jan 08 '19 at 17:58

Since there is Codable, I would strongly recommend you to using it instead of JSONSerialization.

So start with declaring your structs to match with your JSON struct

struct Model: Codable {
    var address: Int
    var reportStatus: String
    var currentLocation: Location
}

struct Location: Codable {
    var latitude, longitude: Double
    var timestamp: String
}

Now just decode your JSON using JSONDecoder

do {
    let data = string.data(using: .utf8)!
    let models = try JSONDecoder().decode([Model].self, from: data)
} catch {
    print(error)
}

... now models is array of Model objects and you can work with it.

score 1 · Answer 2 · answered Jan 08 '19 at 18:07

For sure you should use Codable for this , but for your code to run use

let string = "[{\"address\": 7023000630,\"reportStatus\": \"Retrieved\",\"currentLocation\": {\"latitude\": 29.8529, \"longitude\": 73.99332,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\"} }, {\"address\": 7290098339, \"reportStatus\": \"Retrieved\", \"currentLocation\": {\"latitude\": 21.628569, \"longitude\": 72.996956,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\" } } ]"

let data = string.data(using: .utf8)!

do {
    if let jsonArray = try JSONSerialization.jsonObject(with: data) as? [[ String : Any ]]
    {
        jsonArray.forEach {

            if  let add = $0["address"] as? Int  , let currentLocation = $0["currentLocation"] as? [String:Any], let timestamp = currentLocation["timestamp"] as? String
            {
                print("address is : ", add ,"timestamp is : " , timestamp)
            }
        }

    } else {
        print("bad json")
    }
} catch  {
    print(error)
}

Your obvious problem is here

let address = jsonArray["address"] as! [[String:Any]]

jsonArray is an array that you can't subscript with ["address"]

vadian · Answer 3 · 2019-01-08T18:08:43.283

An array is a list. It can contain multiple items. You have to use a loop to iterate an array (like in your previous question)

The value for key address is Int (no double quotes).

The value for key timestamp is String and is in the dictionary for key currentLocation in the array

let data = Data(string.utf8)
do {
    if let jsonArray = try JSONSerialization.jsonObject(with: data) as? [[String : Any]]
    {
        print(jsonArray) // use the json here
        for item in array {
           let address = item["address"] as! Int
           let currentLocation = item["currentLocation"] as! [String:Any]
           let timestamp = currentLocation["timestamp"] as! String
           print(timestamp)
        }
    } else {
        print("bad json")
    }
} catch {
    print(error)
}

Never use .mutableContainers in Swift. It's pointless.

Bappaditya · Accepted Answer · 2019-01-09T08:55:36.783

In your code snippet jsonArray is an array and array can't subscript a value of type [[String: Any]], so instead you should parse like,

func jsonFour(){
    let string = "[{\"address\": 7023000630,\"reportStatus\": \"Retrieved\",\"currentLocation\": {\"latitude\": 29.8529, \"longitude\": 73.99332,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\"} }, {\"address\": 7290098339, \"reportStatus\": \"Retrieved\", \"currentLocation\": {\"latitude\": 21.628569, \"longitude\": 72.996956,\"timestamp\": \"2019-01-07T16:35:25.079+05:30\" }}]"

    let data = string.data(using: .utf8)!
    do {
        if let jsonArray = try JSONSerialization.jsonObject(with: data, options : JSONSerialization.ReadingOptions.mutableContainers) as? [[String: Any]]
        {
            print(jsonArray) // print the json here
            for jsonObj in jsonArray {
                if let dict = jsonObj as? [String: Any] {
                    if let address = dict["address"] {
                        print(address)
                    }
                    if let location = dict["currentLocation"] as? [String: Any], let timeStamp = location["timestamp"]  {
                        print(timeStamp)
                    }
                }
            }
        } else {
            print("bad json")
        }
    } catch let error as NSError {
        print(error)
    }
}

json not parsing properly

4 Answers4