yoxisem544

import Foundation

class Child: NSObject {
    let name: String
    // KVO-enabled properties must be @objc dynamic
    @objc dynamic var age: Int

    init(name: String, age: Int) {
        self.name = name
        self.age = age

yoxisem544

protocol Constructable {
  init()
}

extension Int {
  
  func of<T: Constructable>(_ this: T.Type) -> [T] {
    guard self > 0 else { return [] }
    return (1...self).map({ _ in T() })
  }

yoxisem544

let jsonData = """
{   "title": "Blah",
    "frontCover": {},
    "backCover": { "image": "", "text": "It's good, read it" }
}
"""

struct BookCover: Decodable {
  var text: String
  var image: String?

yoxisem544

public protocol JSONEmptyRepresentable {
  // 如果建立物件時會遇到 空 json {}，則需要提供自身的 coding keys
  associatedtype CodingKeyType: CodingKey
}

extension KeyedDecodingContainer {
  public func decodeIfPresent<T>(_ type: T.Type, forKey key: K) throws -> T? where T : Decodable & JSONEmptyRepresentable {
    // 先檢查有沒有我們要找的 frontCover key
    if contains(key) {
      // 有的話建立出 nested container

yoxisem544

extension BookCover: JSONEmptyRepresentable {
  typealias CodingKeyType = BookCover.CodingKeys
}

yoxisem544

public protocol JSONBlankRepresentable: RawRepresentable {}

extension KeyedDecodingContainer {
  public func decodeIfPresent<T>(_ type: T.Type, forKey key: K) throws -> T? where T : Decodable & JSONBlankRepresentable, T.RawValue == String {
    if contains(key) {
      if let stringValue = try decodeIfPresent(String.self, forKey: key), stringValue.isEmpty == false {
        return T.init(rawValue: stringValue)
      }
    }
    return nil

yoxisem544

enum Gender {
  case male, female
}

struct User {
  let name: String
  let gender: String // Not good enough
  let gender: Gender // Good
}

yoxisem544

public enum ContentKind : Codable {
  case app(String)
  case movie(Int)
}

extension ContentKind {
  // decode 錯誤拿來丟的錯誤
  enum CodingError: Error { case decoding(String) }
  // 拿來解析的 keys
  enum CodableKeys: String, CodingKey { case app, movie }

yoxisem544

enum SpaceshipKind : String, Codable {
  case transport
  case freighter
  case fighter
  
  enum CodableKeys: String, CodingKey {
    case spaceship = "grand_spaceship"
  }

  enum CodingError: Error { case decodig(String) }

yoxisem544

require 'rest-client'
require 'nokogiri'
require 'open-uri'

class KAIYOUImageGetter

  def initialize
    @counter = 0
    @URL = "http://kai-you.net/article/43334/images/84"
    response = RestClient.get @URL