How to convert JSON String to JSON Object in swift? - ios

Question

I trying to generate JSON Object and convert that to JSON String and that process is Successfully placed. But my real problem rises when I try to convert JSON String to JSON Object. When I try I get nil as result.
func generateJSONObject() {
let jsonObject = createJSONObject(firstName: firstName[0], middleName: middleName[0], lastName: lastName[0], age: age[0], weight: weight[0])
print("jsonObject : \(jsonObject)")
let jsonString = jsonObject.description // convert It to JSON String
print("jsonString : \(jsonString)")
let jsonObjectFromString = convertToDictionary(text: jsonString)
print("jsonObjectFromString : \(String(describing: jsonObjectFromString))")
}
createJSONObject func
// JSON Object creation
func createJSONObject(firstName: String, middleName: String, lastName: String, age: Int, weight: Int) -> [String: Any] {
let jsonObject: [String: Any] = [
"user1": [
"first_name": firstName,
"middle_name": middleName,
"last_name": lastName,
"age": age,
"weight": weight
]
]
return jsonObject
}
convertToDictionary func
func convertToDictionary(text: String) -> [String: Any]? {
if let data = text.data(using: .utf8) {
do {
return try JSONSerialization.jsonObject(with: data, options: []) as? [String: Any]
} catch {
print(error.localizedDescription)
}
}
return nil
}
Logs
When I print JSON Object I get
jsonObject : ["user1": ["age": 21, "middle_name": "Lazar", "last_name": "V", "weight": 67, "first_name": "Alwin"]]
When I print JSON String I get
jsonString : ["user1": ["age": 21, "middle_name": "Lazar", "last_name": "V", "weight": 67, "first_name": "Alwin"]]
Convert JSON String to JSON Object I get below error
The data couldn’t be read because it isn’t in the correct format.
jsonObjectFromString : nil
I don't know why this happening. I want to convert JSON String to JSON Object and I want to parse the JSON.

Answer 1

based on discussion
import Foundation
let firstName = "Joe"
let lastName = "Doe"
let middleName = "Mc."
let age = 100
let weight = 45
let jsonObject: [String: [String:Any]] = [
"user1": [
"first_name": firstName,
"middle_name": middleName,
"last_name": lastName,
"age": age,
"weight": weight
]
]
if let data = try? JSONSerialization.data(withJSONObject: jsonObject, options: .prettyPrinted),
let str = String(data: data, encoding: .utf8) {
print(str)
}
prints
{
"user1" : {
"age" : 100,
"middle_name" : "Mc.",
"last_name" : "Doe",
"weight" : 45,
"first_name" : "Joe"
}
}

Answer 2

Json has to be in Array or Dictionary, it can't be only string so to create a jsonstring first you need to convert to Data format and then convert to String
func generateJSONObject() {
let jsonObject = createJSONObject(firstName: "firstName", middleName: "middleName", lastName: "lastName", age: 21, weight: 82)
print("jsonObject : \(jsonObject)")
if let jsonString = convertToJsonString(json: jsonObject), let jsonObjectFromString = convertToDictionary(text: jsonString) {
print("jsonObjectFromString : \(jsonObjectFromString)")
}
}
func convertToJsonString(json: [String: Any]) -> String? {
do {
let jsonData = try JSONSerialization.data(withJSONObject: json, options: .prettyPrinted)
return String(data: jsonData, encoding: .utf8)
} catch {
print(error.localizedDescription)
}
return nil
}