Concentration Game — Controller

Post in 六 28 三月 2020 |Tags Swift

Controller — ViewController.swift

hook button and controller up:

按住ctrl拖拽进controller的代码
点击dashboard上黄色按钮，拖拽到UI，选择函数

Swift

函数参数（外部名称内部名称：类型）

目的是为了调用函数，以及函数内部都能read like English

@IBAction func touchCard(_ sender: UIButton) {
  flipCard(withEmoji: '👻', on: sender)
}

func flipCard(withEmoji emoji: String, on button: UIButton) {

}

按住option点击函数名查看文档

鼠标放在行号上的圆点可以看到关联的UI

字符串模板: “\()”相当于`${}`，括号内可以放入任何可转化为string的类型

print("flipCard(withEmoji: \(emoji))")

ctrl c, ctrl v可以在界面上复制黏贴一个元素，关联的func也会同样复制，右键点击元素，在Touch Up Inside里看到所有关联的函数，disconnet it

强类型语言

All instance variable has to be intialized

adding an intializer to a class初始化所有变量
直接给变量一个初始值

var flipCount: Int = 0
var flipCount = 0 // swift可根据初始值推断出类型

按住option点击变量名可查看类型

connection:

Action: create a method
Outlet: create an instance variable or property
Outlet Collection: create an array of the things in UI

Swift

@IBOutlet weak var flipCountLabel: UILabel! //感叹号的变量不必初始化

var flipCount = 0 {
  // didSet在每次这个变量更新时调用
  didSet {
    flipCountLabel.text = "Flips: \(flipCount)"
  }
}

Swift

@IBOutlet var cardButtons: [UIButton]!

不能直接更改函数名，会让ui找不到关联的函数，按住command点击函数名，rename it，会改变所有引用的名字

// var emojiChoices: Array<String> = ["🎃", "👻", "🎃", "👻 "]
var emojiChoices = ["🎃", "👻", "🎃", "👻 "]

@IBAction func touchCard(_ sender: UIButton) {
  flipCount += 1;
  // let是常量const
  let cardNumber = cardButtons.index(of: sender) // warning! optional value
  print("cardNumber = \(cardNumber)") // cardNumber = optional(1)

  if let cardNumber = cardButtons.index(of: sender) {
    print("cardNumber = \(cardNumber)")
    flipCard(withEmoji: emojiChoices[cardNumber], on: sender)
  } else {
    print("Chosen card was not iin cardButtons")
  }
}

func index(of element: UIButton) -> Int? // 返回值可选，只有两种状态：int/nil