类和子类的一些例子

最新推荐文章于 2023-03-27 08:19:59 发布

原创最新推荐文章于 2023-03-27 08:19:59 发布 · 481 阅读

1 ·

CC 4.0 BY-SA版权

本文介绍了Swift语言中类的基本定义、属性与方法，并通过具体示例展示了如何使用继承来扩展类的功能。同时，文章还解释了如何实现构造器、重写父类方法等关键概念。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

//关于类的示例

class Shape{//首字母大写
    var numberOfSides = 0
    func simpleDescription() -> String{
        return"A shape with \(numberOfSides) sides."
    }
}

var shape = Shape()//注意编译器要求一定的编程规范
shape.numberOfSides = 7
var sharpeDescription = shape.simpleDescription()

class NamedShape {
    var numberOfSides: Int = 0
    var name: String
    init(name: String){//构造器，用于初始化，deinit析构函数用来在清理中执行一些操作
        self.name = name
    }

    func simpleeDescription() -> String{
        return "A shape wit \(name) sides."
    }
}
var nameShape = NamedShape( name: "Zhangwei")
nameShape.numberOfSides = 7
nameShape.simpleeDescription()

//子类
class Square: NamedShape{//:后为父类名
    var sideLength: Double
    init(sideLength:Double, name: String) {
        self.sideLength = sideLength
        super.init(name: name)
        numberOfSides = 4
    }
    func area() -> Double{
        return sideLength * sideLength
    }
    override func simpleeDescription() -> String {//重写父类方法的话需要override 标记
        return "A square with sides of \(sideLength)"
    }

}
let test = Square(sideLength: 5.2, name: "ZhiMing")
test.area()
test.simpleeDescription()
class EquilateralTriangle: NamedShape{
    var sideLength:Double
    init(sideLength:Double,name: String) {
        self.sideLength = sideLength
        super.init(name: name)
        numberOfSides = 3
    }
    var perimeter:Double{
        get{
            return 3.0 * sideLength
        }
        set{
            sideLength = newValue / 3.0//newVale为新值，如果需要在设置一个新值运行一些代码可以用willSet和didSet
        }
    }
    override func simpleeDescription() -> String {
        return "An equ length\(sideLength)"
    }
}
var triangle = EquilateralTriangle(sideLength: 3.1, name: "a triangle")
triangle.perimeter
triangle.perimeter = 9.9
triangle.sideLength

class TriangleAndSquare {//willSet的示例，不过我并没有完全明白
    var triangle:EquilateralTriangle{
        willSet{
            square.sideLength = newValue.sideLength
        }

    }
    var square:Square{
        willSet{
            triangle.sideLength = newValue.sideLength
        }
    }
    init(size: Double,name: String){
        square = Square(sideLength: size, name: name)
        triangle = EquilateralTriangle(sideLength: size, name: name)
    }
}
var triangleAndSquare = TriangleAndSquare(size: 10, name: "another test shape")
triangleAndSquare.square.sideLength
triangleAndSquare.triangle.sideLength
triangleAndSquare.square = Square(sideLength: 50, name: "larger Square")
triangleAndSquare.triangle.sideLength

let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional square")
let sideLength = optionalSquare?.sideLength