unwrapping

.swift

import UIKit

let jsonData :Data = """

{

"id": 1,
"name": "Leanne Graham",
"username": "Bret",
"email": "[email protected]",
"address": {
"street": "Kulas Light",
"suite": "Apt. 556",
"city": "Gwenborough",
"zipcode": "92998-3874",
}

}

""".data(using: .utf8)!

struct User :Decodable {
    
    let id :Int
    let name :String
    let userName :String
    let email :String
    
    let street :String
    let suite :String
    let city :String
    let zipCode :String
 
    
    public init(from decoder :Decoder) throws {
        
            let userContainer = try decoder.container(keyedBy: UserKeys.self)
            
            self.id = try userContainer.decode(Int.self, forKey: .id)
            self.name = try userContainer.decode(String.self, forKey: .name)
            self.userName = try userContainer.decode(String.self, forKey: .name)
            self.email = try userContainer.decode(String.self, forKey: .email)
        
            let addressContainer = try userContainer.nestedContainer(keyedBy: AddressKeys.self, forKey: .address)
        
            self.street = try addressContainer.decode(String.self, forKey: .street)
            self.suite = try addressContainer.decode(String.self, forKey: .suite)
            self.city = try addressContainer.decode(String.self, forKey: .city)
            self.zipCode = try addressContainer.decode(String.self, forKey: .zipCode)
        
    }
    
    private enum UserKeys :String, CodingKey {
        
        case id
        case name
        case userName = "username"
        case email
        case address
    }
    
    private enum AddressKeys :String, CodingKey {
        
        case street
        case suite
        case city
        case zipCode = "zipcode"
        
    }
}


if let user = try? JSONDecoder().decode(User.self, from: jsonData) {
    print(user.name)
    print(user.userName)
    print(user.street)
} else {
    print("error")
}