codablepRotocolExample.swift

import Foundation
import UIKit

let json = """
[{
"first_name": "Shakti",
"last_name": "prakash",
"age":25,
"address":"Cuttack,Odisha,India"
},
{
"first_name": "Soumen",
"last_name": "Mohanty",
"age":25,
"address":null
}]
"""

let jsonData = Data(json.utf8)

struct Person: Codable{
    var firstName: String
    var lastName: String
    var age: Int
    var  address: String
    private enum CodingKeys: String, CodingKey{
        case firstName = "first_name"
        case lastName = "last_name"
        case age
        case address
        
    }
    init(from decoder: Decoder) throws{
        let container = try decoder.container(keyedBy: CodingKeys.self)
            firstName = try container.decode(String.self, forKey: .firstName)
            lastName = try container.decode(String.self, forKey: .lastName)
            age = try container.decode(Int.self, forKey: .age)
            address = (try container.decodeIfPresent(String.self, forKey: .address)) ?? "Unknown Address"
    }
    
}



let decoder = JSONDecoder()


do {
   let response = try decoder.decode([Person].self, from: jsonData)
    print(response)
} catch let error  {
    print("Parsing Failed \(error.localizedDescription)")
}