Question

我是swift的新手。我正在快速进行App开发练习。类成员初始化器和引用。

我不知道如何解决这个问题。问题是编写自己的初始化程序而不为所有内容提供默认值。

class Spaceship {
    let name: String
    var health: Int = 100
    var position: Int = 0

    func moveLeft() {
        position -= 1
    }

    func moveRight() {
        position += 1
    }

    func wasHit() {
        health -= 5
    }

    init(name:String, health:Int, position:Int) {
        self.name = name
        self.health = health
        self.position = position
    }
}

class Fighter: Spaceship {
    let weapon: String
    var remainingFirePower: Int

    init(weapon:String,remainingFirePower:Int) {
        self.weapon = weapon
        self.remainingFirePower = remainingFirePower
        super.init(name: name, health: health, position: position)
    }

    func fire() {
        if remainingFirePower > 0 {
            remainingFirePower -= 1
        } else {
            print("You have no more fire power.")
        }
    }
}

class ShieldedShip: Fighter {
    var shieldStrength: Int

    override func wasHit() {
        if shieldStrength > 0 {
            shieldStrength -= 5
        } else {
            super.wasHit()
        }
    }
    init(shieldStrength:Int, weapon:String, remainingFirePower:Int){
        self.shieldStrength = shieldStrength
        super.init(weapon:weapon, remainingFirePower:remainingFirePower)
    }
}

Answer 1

了解optional类型。你可以写：

let name: String?
var health: Int?
var position: Int?

Link for optional types

Answer 2

此处为您想要的内容

init(name:String = "ship", health:Int = 100, position:Int = 0) {
    self.name = name
    self.health = health
    self.position = position
}

基本上，你想要像这样设置默认值，如果你只想用默认值初始化它，将NOTHING传递给这个函数，就像这样

super.init()

错误：在属性中使用'self'

2 个答案: