swift4 学习笔记(二)

函数和闭包

用函数来定义一个功能
定义一个函数需要在函数名后面用小括号（）来添加参数，用->来区分参数类型，名称和返回值的类型

func greet(name:String, day:String) -> String {
    return "Hello,\(name),today is \(day)"
}

let greetString = greet(name: "Snow", day: "Monday")

print(greetString)

闭包

let numbers = [1,2,3,4,5,6]
//这个闭包将会轮训数组中的元素，分别给每个元素*3
numbers.map({(number:Int) -> Int in
    let result = number * 3
    return result
})

//讲数组中的item全部*3
numbers.map({ number in number*3})

对象和类

用class+name 来创建一个类
定义类的一个属性和定义一个常量或者变量一样
用var或者let

class Shape {
    var sides = 4
    let corners = 4
    var name:String
    
    init(name:String) {
        self.name = name
    }
    
    func simpleDescription() -> String {
        return "This \(name) have \(sides) side and have \(corners) corners."
    }
}

//在其他类中调用shape类
var shape = Shape(name: "NamedShape")
shape.sides = 8
let descString = shape.simpleDescription()
print(descString)