一、快速入门

1. hello world

var str = "Hello, playground"
println("Hello, world (str)")

2.返回值为函数的函数

func addOne(number: Int) -> Int{
    return 1 + number
}
func makeIncrementer() -> (Int -> Int){
    return addOne
}
var increment = makeIncrementer()
increment(7)

3.参数为函数的函数

func hasAnyMatches(list: [Int], lessThanTen: Int -> Bool) -> Bool{
    for item in list{
        if lessThanTen(item){
            return true
        }
    }
    return false
}

func lessThanTen(number: Int) -> Bool{
    return number < 10
}

var numbers = [20, 19, 9, 12]
hasAnyMatches(numbers, lessThanTen)

4.函数是一种特殊的闭包，除了使用大挂号，也可以使用in隔开闭包名和闭包的内容

numbers.map({
    (number: Int)-> Int in
    let result = 3 * number
    return result
})

闭包的简写

sort(&numbers) { $0 > $1 }

5.类

定义一个类

class Sharp: NSObject {
    var numberOfSides: Int = 0
    var name: String
    
    init(name: String){//构造方法
        self.name = name
    }
    func simpleDescription() -> String {
        return "A sharp with (numberOfSides) sides"
    }
}

继承, init, override, get, set

class EquilateralTriangle: Sharp {//等边三角形
    var sideLength : Double
    //init方法
    init(name: String, sideLength: Double) {
        self.sideLength = sideLength
        super.init(name: name)
        numberOfSides = 3
    }
    //get方法和set方法
    var perimeter: Double{//周长
        get{
            return 3 * sideLength
        }
        set{
            sideLength = newValue / 3.0
        }
    }
    func area() -> Double{
        return sideLength * sideLength
    }
    //覆盖
    override func simpleDescription() -> String {
        return "A EquilateralTriangle with sides of length (sideLength)."
    }
}

6. 属性监视器 

使用willSet, didSet实现

class traingleAndSquare: Sharp {
    var traingle: EquilateralTriangle{
        willSet{
            square.sideLength = newValue.sideLength
        }
    }
    var square: Square{
        willSet{
            traingle.sideLength = newValue.sideLength
        }
    }
    init(size: Double, name: String){
        square = Square(name: name, length: size)
        traingle = EquilateralTriangle(name: name, sideLength: size)
        super.init(name: name)
    }
    
}

参考 https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/TheBasics.html#//apple_ref/doc/uid/TP40014097-CH5-ID309