Swift 4 Decodable: The given data was not valid JSON

Question

I'm trying to write a POST request to my local server, this is my function:

@IBAction func postButtonAction(_ sender: UIButton) {

    guard let url = URL(string:"http://localhost:443/api/message") else {return}
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    print("POSTED")

    let date : Date = Date()
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
    let dateTime = dateFormatter.string(from: date)

    let newPost = MessageForPost(message: "Hi", timestamp: dateTime, latitude: "1.1", longitude: "2.2")
    let newData = DataForPost(message: newPost)
    let newPackage = PackageForPost(data: newData)

    do {
        let jsonBody = try JSONEncoder().encode(newPackage)
        request.httpBody = jsonBody
        print("jsonBody:",jsonBody)
        let jsonBodyString = String(data: jsonBody, encoding: .utf8)
        print("JSON String : ", jsonBodyString!)
    } catch let err  {
        print("jsonBody Error: ",err)
    }

    let session = URLSession.shared
    let task = session.dataTask(with: request){ (data,response,err) in

        guard let data = data else {return}

        do{
            let sendPost = try JSONDecoder().decode(PackageForPost.self, from: data)
            print("DATA:\(data)")
        }catch let err{

            print("Session Error: ",err)
        }
    }
    task.resume()
}

These are the structs using here:

struct PackageForPost:Encodable, Decodable{
    let data: DataForPost
}

struct DataForPost:Encodable, Decodable{
    let message: MessageForPost
}

struct MessageForPost:Codable {
    let message: String
    let timestamp: String
    let latitude: String
    let longitude: String
}

And it was able to print

JSON String :  {"data":{"message":{"message":"Hi","timestamp":"2017-10-18 00:50:13","latitude":"1.1","longitude":"2.2"}}}

But it keeps showing this ERROR:

Session Error: dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "JSON text did not start with array or object and option to allow fragments not set." UserInfo={NSDebugDescription=JSON text did not start with array or object and option to allow fragments not set.})))

Why is it not a valid JSON???

Here's my server's API POST request document:

POST
/api/message

{
    data: {
        message: {

            message: “Hey, a new message!”,
            timestamp: 2017-09-10 10:22:33,
            latitude: 62.233589156441724,
            longitude: 25.735066461654696
        }
   } 
}

I've done quite some googling but am stuck here for a very long time! Any help appreciated!

Answer 1

It was simple... I had the same kind of issue.

Look your Struct is Decoding and Encoding Timestamp, latitude and longitude as Strings and JSON is in Double or Floating type.

struct MessageForPost:Codable {
    let message: String
    let timestamp: String
    let latitude: String
    let longitude: String
}

And here JSON

{
    data: {
        message: {
            message: "Hey, a new message!",
            timestamp: 2017-09-10 10:22:33,
            latitude: 62.233589156441724,
            longitude: 25.735066461654696
        }
   } 
}

.... I fixed it at my end and... it worked...

Edited use the same data type...