（1）参数类型为可选型Optional. 如果参数为空，则输出??后面的字符串，否则输出可选型的参数值。

import Foundation

func sayHello(name:String?)->String{

  let result = "Hello," + (name ?? "无名氏")
  return result

}

var nickname:String?
nickname = "Jack"
println(sayHello(nickname))

（3）使用元祖让函数返回多个值。

import Foundation

let userscores = [12,90,45,3,213,45]

func maxMinscores(scores:[Int]) -> (maxscores:Int,minscores:Int){

  var curmax = scores[0]
  var curmin = scores[0]
  
  for score in scores[1 ..< scores.count]{

    curmax = max(curmax,score)//Swift中的全局函数；
    curmin = min(curmin,score)
    
    
  }
  
  return (curmax,curmin)
  
}

let result = maxMinscores(userscores)
println("最大值：\(result.maxscores)" )
println("最小值：\(result.minscores)" )

或者：

import Foundation

let userscores = [12,45]

func maxMinscores(scores:[Int]) -> (Int,Int){

  var curmax = scores[0]
  var curmin = scores[0]
  
  for score in scores[1 ..< scores.count]{

    curmax = max(curmax,curmin)
  
}

let result = maxMinscores(userscores)
println("最大值：\(result.0)" )
println("最小值：\(result.1)" )

import Foundation

let userscores = [12,45]

func maxMinscores(scores:[Int]) -> (maxscore:Int,minscore:Int)?{

  //如果传入的参数数组为空，则返回nil；
  if scores.isEmpty{
  
    return nil
  }
  
  
  var curmax = scores[0]
  var curmin = scores[0]
  
  for score in scores[1 ..< scores.count]{

    curmax = max(curmax,curmin)
  
}

//返回的是一个可选型；
if let result = maxMinscores(userscores){

  println("最大值：\(result.maxscore)" )
  println("最小值：\(result.minscore)" )
  
}

import Foundation

var userscores:[Int]? = [1,2,4,5,6]

func maxMinscores(scores:[Int]) -> (maxscore:Int,minscore:Int)?{
  
  //如果传入的参数数组为空，则返回nil；
  if scores.isEmpty{
    
    return nil
  }
  
  
  var curmax = scores[0]
  var curmin = scores[0]
  
  for score in scores[1 ..< scores.count]{
    
    curmax = max(curmax,curmin)
  
}

//返回的是一个可选型；

userscores = userscores ?? []
if let result = maxMinscores(userscores!){
  
  println("最大值：\(result.maxscore)" )
  println("最小值：\(result.minscore)" )
  
}

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