Swift

//: Playground - noun: a place where people can play

import UIKit

func add(a:Int, b:Int) -> Int
{
    return a + b
}

// 其中, (Int, Int) -> Int 就是显式的声明函数类型
let anotherAdd:(Int, Int) -> Int = add
anotherAdd(3, 4)

/*--------------------------------------------------------------------*/

func sayHello(nickName:String)
{
    print("Hello, (nickName)")
}

// 这里需要注意的是无返回值的函数类型的声明格式
let anotherGreeting:(String) -> Void = sayHello
anotherGreeting("Rinpe Chan")
// 或者写成
let greeting:(String) -> () = sayHello
greeting("BoBo")
// 或者写成(只有一个参数的时候有效)
let anotherHello:String -> () = sayHello
anotherHello("my son")

/*------------------------------举个栗子--------------------------------*/

// 假设老师要对两组学生的分数进行不同操作

func changeScores1(inout scores:[Int]) {
    for index in 0..<scores.count {
        scores[index] += 3
    }
}

func changeScores2(inout scores:[Int]) {
    for index in 0..<scores.count {
        scores[index] -= 5;
    }
}

var scores1 = [36, 61, 78, 99, 100]
changeScores1(&scores1)

var scores2 = [12, 45, 76, 88, 96]
changeScores2(&scores2)

// 其实对于上面两个方法, 只是for循环里面的内容不同, 也就是老师对分数的操作
// 可以简化为:

func changeScores(op:(Int) -> Int, inout scores:[Int]) {
    for index in 0..<scores.count {
        op(scores[index])
    }
}

func op1(originScore:Int) -> Int {
    return originScore + 3
}

func op2(originScore:Int) -> Int {
    return originScore - 5
}


changeScores(op1, scores: &scores1)
changeScores(op2, scores: &scores2)