//part1
//函数
func sayHello(name:String?)->String{//->String表示返回一个字符串类型let result = "hello,"+(name ?? "Guest")//当字符串为空时，name为guestreturn result;
}var nickname:String?//声明一个可选型的字符串
println(sayHello(nickname))//part2
//通过元祖可以返回多个值
func maxminSores(score:[Int])->(maxscore:Int,minscore:Int)?{//返回一个可选值元祖if score.isEmpty{//当数组为空时return nil}var curmax = score[0],curmin = score[0]//初始化最大最小值为第一个数for score in score[1..<score.count]//1到count－1
    {curmax = max(curmax, score)curmin = min(curmin, score)}return (curmax,curmin)
}var userScores:[Int]? = [12,990,572,3258,9999,1204]
userScores = userScores ?? []//当数组为空时userScores=[]
if let (maxV,minV) = maxminSores(userScores!){
maxV
minV
}//part3
//保留oc特性中的外部参数名
//#表示外表参数名跟内部一致，定义函数允许赋予默认值，有默认值的参数要放在后面
func sayHi(userName name:String?,# greet:String,others:String=". how do you do")->String{//->String表示返回一个字符串类型let result = "\(greet),"+(name ?? "Guest")+others//当字符串为空时，name为guestreturn result;
}
sayHi(userName: "forr", greet: "hi")
//part4
//设置可变参数others:Int...
//函数的参数排序：先是必须的参数，再到带默认值的参数，最后是可变的参数
//函数中的参数默认是let不可变的，且属于值传递,
func add(var a:Int,b:Int,others:Int...)->Int{var result = a+bfor num in others{result += num}a = 1000return result
}
var a = 2
var res = add(a,3, 4)
a
////part4
//通过inout声明参数实现“址传递”
func swapTwoInts(inout a:Int,inout b:Int){let t = aa = bb = t
}var x = 0,y = 100
x
yswapTwoInts(&x, &y)
x
y
////part5
//通过变量存在一个函数,此时给出变量的类型为:(Int,Int,Int...)->Int
let anotherAdd:(Int,Int,Int...)->Int = add
anotherAdd(6,3,1)func sayYes(){print("yes")
}
let anotherSayYes:()->() = sayYes
sayYes()
////part6
//将一个函数用作另一个函数的参数,:(Int)->Int表示变量的类型是一个函数类型
func changeScores(op:(Int)->Int,inout scores:[Int]){for i in 0..<scores.count{scores[i] = op(scores[i])//调用函数op(scores[i])
    }
}func op1(x:Int)->Int{return Int(sqrt(Double(x))*10)}
func op2(x:Int)->Int{return Int(Double(x)/150.0*100)}
func op3(x:Int)->Int{return x + 3}var scores1 = [36,61,78,99]
changeScores(op1 , &scores1)var scores2 = [88,101,124,137,150]
changeScores(op2  , &scores2)var scores3 = [59,61,76,83,95]
changeScores(op3 , &scores3)//使用系统sorted对数组降序
var arr = [Int]()
for _ in 1...20{arr.append(Int(arc4random()%100))
}
sorted(arr)func compareTwoInts(a:Int,b:Int)->Bool{return a>b//降序
}
sorted(arr, compareTwoInts)//第二个参数传一个定义好降序规则的函数////part7函数式编程
//将一个函数用作另一个函数的返回值
func tier1MailFee(weight:Int)->Int{return 1*weight;
}func tier2MailFee(weight:Int)->Int{return 2*weight;
}
//(Int)->Int表示返回值的类型是一个函数类型
func chooseMailFeeCalcMethod(weight:Int)->(Int)->Int{return (weight <= 10) ? tier1MailFee : tier2MailFee
}func totalPrice(price:Int,weight:Int)->Int{let mailFeeCalc:(Int)->Int = chooseMailFeeCalcMethod(weight)//定义一个接收函数的变量return mailFeeCalc(weight) + price * weight//4+8
}totalPrice(2, 4)
totalPrice(1, 12)//函数内可嵌套函数
//func totalPrice(price:Int,weight:Int)->Int{
//    func chooseMailFeeCalcMethod(weight:Int)->(Int)->Int{
//        return (weight <= 10) ? tier1MailFee : tier2MailFee
//    }
//    let mailFeeCalc:(Int)->Int = chooseMailFeeCalcMethod(weight)//定义一个接收函数的变量
//    return mailFeeCalc(weight) + price * weight
//}

//嵌套函数
func getMathFunc(#type:String)->(Int)->Int{func squre(num:Int)->Int{return num * num;}func cube(num:Int)->Int{return num * num * num;}switch(type){case "squre":return squre;default:return cube;}
}var squre:(Int)->Int = getMathFunc(type: "squre");println(squre(4));

///part1闭包相当匿名函数
//闭包{(a:Int,b:Int)->Bool in return a>b}
sorted(arr, {(a:Int,b:Int)->Bool in return a>b//in关键字
})
arrvar strArr = ["d","cd","bcd","abcd","abc","ab","a"]
strArr = sorted(strArr, {(s1:String,s2:String)->Bool inif countElements(s1) != countElements(s2){return countElements(s1) < countElements(s2)//字母个数少的在前面
    }return s1 < s2//升序
})sorted(arr,{a,b in return a>b})//简短版
sorted(arr,{$0 > $1})//降序，$0,$1表示第一二个参数
sorted(arr, >)//操作符作函数传入，该话题后续
///part2
//结尾闭包trailing closure
strArr = sorted(strArr) {(s1:String,s2:String)->Bool inif countElements(s1) != countElements(s2){return countElements(s1) < countElements(s2)//字母个数少的在前面
    }return s1 < s2//升序
}
//闭包内可以访问外边变量，后续相关的内存管理
var datas = [0,1,2,3,4,5,6,7,8,9,10]
var num = 3
datas = sorted(datas){return fabs(CGFloat($0-num)) < fabs(CGFloat($1-num))
}
///part3
//函数和闭包都属于引用类型，其他数据类型属于值类型
func calcTotalMiles(todayMiles:Int)->()->Int{var totalMiles = 0//与一般函数中的变量差别很大，通常其他语言函数里定义的变量都是存放在栈区，调研函数后，定义的变量通通会销毁return {totalMiles += todayMiles;return totalMiles}//闭包
}var dailyTwoMiles = calcTotalMiles(2)
dailyTwoMiles()
dailyTwoMiles()
dailyTwoMiles()var myPlan = dailyTwoMiles
myPlan()
dailyTwoMiles()

//闭包的简化形式
//        var squre:(Int)->Int = {(num) in return num * num }
//        println(squre(4));//        var squre:(Int)->Int = {num in return num * num }
//        println(squre(4));//省略形参名，通过$0、$1...来引用第一个、第二个参数var squre:(Int)->Int = {$0 * $0}println(squre(4));//
        var result:Int = {var result = 1;for i in 1...$1{result *= $0;}return result;}(4,3)//{}表示闭包     (,)表示调用println("\(result)")