Convert Json string to Json object in Swift 4

I try to convert JSON string to a JSON object but after JSONSerialization the output is nil in JSON.

Response String:

[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]

I try to convert this string with my code below:

let jsonString = response.result.value
let data: Data? = jsonString?.data(using: .utf8)
let json = (try? JSONSerialization.jsonObject(with: data, options: [])) as? [String:AnyObject]
 print(json ?? "Empty Data")

The problem is that you thought your jsonString is a dictionary. It's not.

It's an array of dictionaries. In raw json strings, arrays begin with [ and dictionaries begin with {.

---

I used your json string with below code :

let string = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]"
let data = string.data(using: .utf8)!
do {
    if let jsonArray = try JSONSerialization.jsonObject(with: data, options : .allowFragments) as? [Dictionary<String,Any>]
    {
       print(jsonArray) // use the json here     
    } else {
        print("bad json")
    }
} catch let error as NSError {
    print(error)
}

and I am getting the output :

[["form_desc": <null>, "form_name": Activity 4 with Images, "canonical_name": df_SAWERQ, "form_id": 3465]]

Using JSONSerialization always felt unSwifty and unwieldy, but it is even more so with the arrival of Codable in Swift 4. If you wield a [String:Any] in front of a simple struct it will ... hurt. Check out this in a Playground:

import Cocoa

let data = "[{\"form_id\":3465,\"canonical_name\":\"df_SAWERQ\",\"form_name\":\"Activity 4 with Images\",\"form_desc\":null}]".data(using: .utf8)!

struct Form: Codable {
    let id: Int
    let name: String
    let description: String?
    
    private enum CodingKeys: String, CodingKey {
        case id = "form_id"
        case name = "form_name"
        case description = "form_desc"
    }
}

do {
    let f = try JSONDecoder().decode([Form].self, from: data)
    print(f)
    print(f[0])
} catch {
    print(error)
}

With minimal effort handling this will feel a whole lot more comfortable. And you are given a lot more information if your JSON does not parse properly.

I tried the solutions here, and as? [String:AnyObject] worked for me:

do{
    if let json = stringToParse.data(using: String.Encoding.utf8){
        if let jsonData = try JSONSerialization.jsonObject(with: json, options: .allowFragments) as? [String:AnyObject]{
            let id = jsonData["id"] as! String
            ...
        }
    }
}catch {
    print(error.localizedDescription)
    
}

I used below code and it's working fine for me. :

let jsonText = "{\"userName\":\"Bhavsang\"}"
var dictonary:NSDictionary?
    
if let data = jsonText.dataUsingEncoding(NSUTF8StringEncoding) {
        
     do {
            dictonary =  try NSJSONSerialization.JSONObjectWithData(data, options: [.allowFragments]) as? [String:AnyObject]
        
            if let myDictionary = dictonary
              {
                  print(" User name is: \(myDictionary["userName"]!)")
              }
            } catch let error as NSError {
            
            print(error)
         }
}

static func getJSONStringFromObject(object: Any?) -> String? {
    do {
        let jsonData = try JSONSerialization.data(withJSONObject: object ?? DUMMY_STRING, options: [])
        return String(data: jsonData, encoding: .utf8) ?? DUMMY_STRING
    } catch {
        print(error.localizedDescription)
    }
    return DUMMY_STRING
}