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

import UIKit

//swift 第四课 函数与闭包

//1.函数的用法
func greet(name: String, day: String) ->String {

return "Hello \(name), today is \(day)"

}

greet("Bob","Tuesday")


//2.多返回值的函数
func calculateStatistics(scores: [Int]) ->(min: Int, max: Int, sum: Int){

var min = scores[0]

var max = scores[0]

var sum = 0

for score in scores{

if score > max {

max = score

}else if score < min{

min = score

}

sum += score

}

return (min, max, sum)

}

let statistics = calculateStatistics([5, 3, 100, 3, 9])

print(statistics.sum)

print(statistics.2)

//3.不限参数个数的函数
func sumOf(numbers: Int...) -> Int {

var sum = 0

for number in numbers{

sum += number

}

return sum

}

sumOf()

sumOf(42, 597, 12)

//4.嵌套函数
func returnFifteen() -> Int{

var y = 10

func add(){

y += 5

}

add()

return y

}

returnFifteen()

//5.函数可以作为函数的返回值
func makeIncrementer() -> (Int -> Int){

func addOne(number: Int) -> Int {

return 1 + number

}

return addOne

}

var increment = makeIncrementer()

increment(7)

//5.函数也可以作为函数的参数
func hasAnyMatches(list: [Int], condition: Int -> Bool) -> Bool {

for item in list {

if condition(item) {

return true

}

}

return false

}

func lessThanTen (number: Int) -> Bool {

return number < 10

}

var numbers = [20, 19, 5, 12]

hasAnyMatches(numbers, lessThanTen)


//6.闭包的使用
//首先介绍一下map方法的定义：返回一个数组，这个数组内的元素是原数组经过闭包函数计算返回的值

numbers.map({

(number: Int) -> Int in

let result = 3 * number

return result

})

//简写方式
let mappedNumbers = numbers.map({

number in 3 * number

})

print(mappedNumbers)

//利用闭包排序
let sortedNumbers = numbers.sorted {

$0 > $1

}

print(sortedNumbers)

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

import UIKit

//Swift 第三课 分支与循环

//1.if else 与 for in 循环

let individualScores = [75, 43, 103, 87, 12]

var teamScore = 0

for score in individualScores {

if score > 50 {

teamScore += 3;

} else {

teamScore += 1;

}

}

print(teamScore)

//2.用"?"来声明可选变量

var optionalString: String? = "Hello"

print(optionalString == nil)

var optionalName: String? = "John Appleseed"

var greeting = "Hello!"

//3.用 if let 来进行快速判断可选变量是否为空

if let name = optionalName {

greeting = "Hello, \(name)"

}

//print(name) 请记住name并没有声明变量，它只在if let 作用域内有效

//4.switch用法

let vegetable = "red pepper"

switch vegetable {

case "celery":

let vegetableComment = "Add some raisins and make ants on a log."

case "cucumber","watercress":

let vegetableComment = "That would make a good tea sandwich."

case let x where x.hasSuffix("pepper"):

let vegetableComment = "Is it a spicy \(x)?"

default:

let vegetableComment = "Everything tastes good in soup."

}


//5.利用for in 快速遍历字典

let interestingNumbers = [

"Prime": [2, 3, 5, 7, 11, 13],

"Fibonacci": [1, 1, 2, 3, 5, 8],

"Square": [1, 4, 9, 16, 25]

]

var largest = 0

for (kind, numbers) in interestingNumbers{

for number in numbers{

if number > largest {

largest = number

}

}

}

print(largest)


//6.while repeat循环

var n = 2

while n < 100{

n = n * 2

}

print(n)


//var m = 2  //repeat这个语法可能被cut掉了，现在不能使用
//
//repeat{
//    
//    m = m * 2
//    
//}while m < 100
//
//print(m)

//6. for 的简便写法

var firstForLoop = 0

for i in 0..<4 {

firstForLoop += i

}

print(firstForLoop)


var secondForLoop = 0

for var i = 0; i < 4; ++i {

secondForLoop += i

}

print(secondForLoop)

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

import UIKit

//swift 第二课 数组与字典

//1.数组的声明

var shoppingList = ["catfish","water","tulips","blue paint"]

shoppingList[1] = "bottle of water"

print(shoppingList)

//2.字典的声明

var occupations = ["Malcolm":"Captain","Kaylee":"Mechanic"]

occupations["Jayne"] = "Public Relations"

print(occupations)

//3.空数组和空字典的声明

let emptyArray = [String]()

let emptyDictionary = [String : Float]()

//甚至你可以这样清空数组

shoppingList = []

occupations = [:]

var dateFormatter = NSDateFormatter()

dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss"

let date = dateFormatter.dateFromString("1990-04-15 00:00:00")