Automatic JSON serialization and deserialization of objects in Swift

Question

I\'m looking for a way to automatically serialize and deserialize class instances in Swift. Let\'s assume we have defined the following class …

class Person          


        

Answer 1

With Swift 4, you simply have to make your class conform to Codable (Encodable and Decodable protocols) in order to be able to perform JSON serialization and deserialization.

import Foundation

class Person: Codable {
    let firstName: String
    let lastName: String

    init(firstName: String, lastName: String) {
        self.firstName = firstName
        self.lastName = lastName
    }
}

Usage #1 (encode a Person instance into a JSON string):

let person = Person(firstName: "John", lastName: "Doe")
let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted // if necessary
let data = try! encoder.encode(person)
let jsonString = String(data: data, encoding: .utf8)!
print(jsonString)

/*
 prints:
 {
   "firstName" : "John",
   "lastName" : "Doe"
 }
 */

Usage #2 (decode a JSON string into a Person instance):

let jsonString = """
{
  "firstName" : "John",
  "lastName" : "Doe"
}
"""

let jsonData = jsonString.data(using: .utf8)!
let decoder = JSONDecoder()
let person = try! decoder.decode(Person.self, from: jsonData)
dump(person)

/*
 prints:
 ▿ __lldb_expr_609.Person #0
   - firstName: "John"
   - lastName: "Doe"
 */