ios - Swift4.2 : Why func gameDidEnd(_:) no need to use game parameter but still declare in the function?

Question

根据swift.org上的文档，原始源代码如下:

https://docs.swift.org/swift-book/LanguageGuide/Protocols.html

class DiceGameTracker: DiceGameDelegate {
    var numberOfTurns = 0
    func gameDidStart(_ game: DiceGame) {
        numberOfTurns = 0
        if game is SnakesAndLadders {
            print("Started a new game of Snakes and Ladders")
        }
        print("The game is using a \(game.dice.sides)-sided dice")
    }
    func game(_ game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int) {
        numberOfTurns += 1
        print("Rolled a \(diceRoll)")
    }
    func gameDidEnd(_ game: DiceGame) {
        print("The game lasted for \(numberOfTurns) turns")
    }
}

我知道 func gameDidStart 使用类型 DiceGame 游戏参数来访问 .dice.sides，并检查引用对象。

但是 func gameDidEnd(_ game: DiceGame) 和 func game(_ game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int) 这两个函数没有使用游戏参数，为什么还要声明呢？它是Apple的编码风格吗？我真的不明白这部分....

Answer 1

简单的回答是肯定的，这是 Apple 深思熟虑的选择。该参数是协议(protocol)方法声明的必需部分:

protocol DiceGameDelegate: AnyObject {
    func gameDidStart(_ game: DiceGame)
    func game(_ game: DiceGame, didStartNewTurnWithDiceRoll diceRoll: Int)
    func gameDidEnd(_ game: DiceGame)
}

因此，为了符合协议(protocol)，无论您是否使用它，它都必须包含该参数。