Swift – Codable

what is it

• Allows creation of Swift object directly from JSON and vice versa
• Introduced in Swift 4.0

How to use:

• Derive your class/struct from Codeable

 struct Student : Codable {
	var name : String
	var roll_no: String
	var class : String
 }

• Creating swift object from JSON string

let jsonData = jsonString.data(using: .utf8)
    let student = try JSONDecoder().decoder (Student.self, from jsonData)
    print (student.name)

• use CodingKey when the Json variable is different from struct variable name

 struct Student : Codable {
	var name : String
	var rollNo: String
	var class : String

	enum CodingKeys: String, CodingKey {
       	 case name = “student_name”
       	 case rollNo = “roll_no”
       	 case class
   	 }

 }

• Encoding is equally straight forward

let jsonData = try! JSONEncoder().encode(student)
let jsonString = String(data: jsonData, encoding: .utf8)!

• Working with array of objects

let students = try! JSONDecoder().decode([Student].self, from: jsonData)

• Working with nested objects
  Its just the same, as with simple objects, define nested struct and ensure using top level struct (which also should be a Codeable) to encode/decode