การจัดการชนิดค่าเสริมและชนิดซ้อนกัน

import Foundation

struct User: Codable {
    var name: String
    var nickname: String?
}

let json = "{\"name\":\"Ada\"}"
let u = try JSONDecoder().decode(User.self, from: json.data(using: .utf8)!)
print(u.name, u.nickname ?? "-")

import Foundation

struct User: Codable {
    var name: String
    var nickname: String?
}

let data = try JSONEncoder().encode(User(name: "Ada", nickname: nil))
print(String(data: data, encoding: .utf8)!)

import Foundation

struct User: Codable {
    var name: String
    var age: Int?
}

let json = "{\"name\":\"Ada\",\"age\":null}"
let u = try JSONDecoder().decode(User.self, from: json.data(using: .utf8)!)
print(u.age == nil)

import Foundation

struct Address: Codable { var city: String; var zip: String }
struct Person: Codable { var name: String; var address: Address }

let p = Person(name: "Lee", address: Address(city: "Rome", zip: "00100"))
let data = try JSONEncoder().encode(p)
print(String(data: data, encoding: .utf8)!)

import Foundation

struct Address: Codable { var city: String }
struct Person: Codable { var name: String; var address: Address }

let json = "{\"name\":\"Lee\",\"address\":{\"city\":\"Rome\"}}"
let p = try JSONDecoder().decode(Person.self, from: json.data(using: .utf8)!)
print(p.address.city)

import Foundation

struct Address: Codable { var city: String }
struct Person: Codable { var name: String; var address: Address? }

let json = "{\"name\":\"Lee\"}"
let p = try JSONDecoder().decode(Person.self, from: json.data(using: .utf8)!)
print(p.address?.city ?? "no address")

import Foundation

struct Tag: Codable { var name: String }
struct Post: Codable { var title: String; var tags: [Tag] }

let p = Post(title: "Hi", tags: [Tag(name: "swift"), Tag(name: "json")])
let data = try JSONEncoder().encode(p)
print(String(data: data, encoding: .utf8)!)

import Foundation

struct Tag: Codable { var name: String }

let json = "[{\"name\":\"a\"},{\"name\":\"b\"}]"
let tags = try JSONDecoder().decode([Tag].self, from: json.data(using: .utf8)!)
for t in tags { print(t.name) }

import Foundation

struct Box: Codable { var items: [String]? }

let a = try JSONDecoder().decode(Box.self, from: "{}".data(using: .utf8)!)
let b = try JSONDecoder().decode(Box.self, from: "{\"items\":[]}".data(using: .utf8)!)
print(a.items == nil, b.items == [])

import Foundation

struct Comment: Codable { var text: String }
struct Article: Codable { var title: String; var comments: [Comment] }
struct Feed: Codable { var articles: [Article] }

let feed = Feed(articles: [Article(title: "A", comments: [Comment(text: "hi")])])
let data = try JSONEncoder().encode(feed)
print(String(data: data, encoding: .utf8)!)

import Foundation

struct Address: Codable { var city: String }
struct Person: Codable {
    var name: String
    var address: Address?
    var hobbies: [String]
}

let p = Person(name: "Mo", address: Address(city: "Cairo"), hobbies: ["chess"])
let data = try JSONEncoder().encode(p)
let back = try JSONDecoder().decode(Person.self, from: data)
print(back.address?.city ?? "-", back.hobbies.first ?? "-")