var a = 123 //a为Int
let b = "helo" //b为String
var 猫叫 ＝ "喵"

let i = 1
if i {
 //编译报错
}

if i == 1 {
}

typealias 音频采样 = UInt16

var jserme = ("183cm", 26, "76kg")

println(jserme.0) //返回183cm

let jserme = ("183cm",26,"76kg")
let (身高, 年龄, 体重) = jserme
println("身高是 \(身高)")

let jserme = (身高:"183cm",年龄:26,体重:"76kg")
println("身高是 \(jserme.身高)")

for char in "一言既出"{
 println(char)
}
 
/*
一
言
既
出
*/

var 字符串 = "我是字符串"
var 空字符串 = ""
 
if 空字符串.isEmpty {
 println("这是一个空的字符串")
}
 
if 空字符串 == "" {
 println("这是一个空的字符串")
}

var 成语数组 = [
 "一言既出",
 "一触即发",
 "一呼百应",
 "一槌定音",
 "一无所有",
 "一生一世",
 "一见钟情"
]
 
var count = 0
for 成语 in 成语数组 {
 if(成语.hasPrefix("一")){
  count++
 }
}
 
println(count) //输出7

var 一串 = "我是字符串一"
var 二串 = 一串
 
二串 = "我是字符串二"
 
println("字符串一:\(一串)， 字符串二:\(二串)")

var 成语数组 = [
 "一言既出",
 "一触即发",
 "一呼百应"
]
 
for i in 0..成语数组.count {
 println("第\(i)个成语是:\(成语数组[i])")
}
//这里如何使用...会报错，因为成语数组[3]是没有值的

var 购物清单: String[] = ["鸡蛋", "牛奶"]
//也可以是下面的这样
//var 购物清单 = ["鸡蛋", "牛奶"]

var 购物清单 = ["鸡蛋", "牛奶"]
 
购物清单.append("苹果")
 
购物清单 += "草莓"
 
println("\(购物清单)") //[鸡蛋, 牛奶, 苹果, 草莓]

var 购物清单 = ["鸡蛋", "牛奶"]
 
println("\(购物清单[0])") //鸡蛋
println("\(购物清单[0..1])") //[鸡蛋]
println("\(购物清单[0...1])") //[鸡蛋, 牛奶]
println("\(购物清单[0...2])") //[鸡蛋, 牛奶, ]

var airports: Dictionary<String, String> = ["TYO": "Tokyo", "DUB": "Dublin"]
 
//也可以简化为
//var airports = ["TYO": "Tokyo", "DUB": "Dublin"]

airports["BJ"] = "Beijin"

for var index = 0; index < 3; index++ {
 println("index is \(index)")
}
//index is 0
//index is 1
//index is 2

func sayHello(personName: String) -> String {
 let greeting = "Hello, " + personName + "!"
 return greeting
}
 
println(sayHello("jserme"))

func info(word:String = "aha") -> (length:Int, containA:Bool){
 var containA = false
 for char in word {
  if( char == "a") {
   containA = true
   break
  }
 }
 
 return (word.utf16count, containA)
}
 
println(info(word: "波波")) //(2, false)
println(info()) //(3, true)

func join(string s1: String, toString s2: String, withJoiner joiner: String)
 -> String {
 return s1 + joiner + s2
}
 
//调用的时候
join(string: "hello", toString: "world", withJoiner: ", ")
// returns "hello, world"

func containsCharacter(#string: String, #characterToFind: Character) -> Bool {
 for character in string {
  if character == characterToFind {
   return true
  }
 }
 return false
}
let containsAVee = containsCharacter(string: "aardvark", characterToFind: "v")
// containsAVee equals true, because "aardvark" contains a "v"

func alignRight(var string: String, count: Int, pad: Character) -> String {
 let amountToPad = count - countElements(string)
 for _ in 1...amountToPad {
  string = pad + string
 }
 return string
}
 
let originalString = "hello"
let paddedString = alignRight(originalString, 10, "-")
// paddedString is equal to "-----hello"
// originalString is still equal to "hello"

func swapTwoInts(inout a: Int, inout b: Int) {
 let temporaryA = a
 a = b
 b = temporaryA
}
var someInt = 3
var anotherInt = 107
swapTwoInts(&someInt, &anotherInt)
println("someInt is now \(someInt), and anotherInt is now \(anotherInt)")
// prints "someInt is now 107, and anotherInt is now 3"

func addTwoInts(a: Int, b: Int) -> Int {
 return a + b
} //函数类型为 (Int, Int) -> Int
func multiplyTwoInts(a: Int, b: Int) -> Int {
 return a * b
}//函数类型为 (Int, Int) -> Int
 
//接收名为mathFunction的函数类型
func printMathResult(mathFunction: (Int, Int) -> Int, a: Int, b: Int) {
 println("Result: \(mathFunction(a, b))")
}
printMathResult(addTwoInts, 3, 5)
// prints "Result: 8"
 
//返回函数类型
func stepForward(input: Int) -> Int {
 return input + 1
}
func stepBackward(input: Int) -> Int {
 return input - 1
}
func chooseStepFunction(backwards: Bool) -> (Int) -> Int {
 return backwards ? stepBackward : stepForward
}
var currentValue = 3
let moveNearerToZero = chooseStepFunction(currentValue > 0)
// moveNearerToZero now refers to the stepBackward() function

let names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
 
func backwards(s1: String, s2: String) -> Bool {
 return s1 > s2
}
var reversed = sort(names, backwards)
println(reversed)
// reversed is equal to ["Ewa", "Daniella", "Chris", "Barry", "Alex"]s

let names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
 
var reversed = sort(names, {(s1:String, s2:String) -> Bool in
 return s1 > s2
})
println(reversed)
// reversed is equal to ["Ewa", "Daniella", "Chris", "Barry", "Alex"]

let names = ["Chris", "Alex", "Ewa", "Barry", "Daniella"]
 
var reversed = sort(names, { s1, s2 in s1 > s2 } )
 
println(reversed)

enum Barcode {
 case UPCA(Int, Int, Int) = (1,2,3)
 case QRCode(String) = "hello"
}

struct Resolution {
 var width = 0
 var heigth = 0
}
class VideoMode {
 var resolution = Resolution()
 var interlaced = false
 var frameRate = 0.0
 var name: String?
}

let someResolution = Resolution()
let someVideoMode = VideoMode()

println("The width of someVideoMode is \(someVideoMode.resolution.width)")
someVideoMode.resolution.width = 12880
println("The width of someVideoMode is now \(someVideoMode.resolution.width)")

let vga = resolution（width:640, heigth: 480）

class DataImporter {
 /*
 DataImporter 是一个将外部文件中的数据导入的类。
 这个类的初始化会消耗不少时间。
 */
 var fileName = "data.txt"
 // 这是提供数据导入功能
}
 
class DataManager {
 @lazy var importer = DataImporter()
 var data = String[]()
 // 这是提供数据管理功能
}
 
let manager = DataManager()
manager.data += "Some data"
manager.data += "Some more data"
// DataImporter 实例的 importer 属性还没有被创建

struct AlternativeRect {
 var origin = Point()
 var size = Size()
 var center: Point {
 get {
  let centerX = origin.x + (size.width / 2)
  let centerY = origin.y + (size.height / 2)
  return Point(x: centerX, y: centerY)
 }
 set { //这里setter 没有定义表示新值的参数名，则可以使用默认名称newValue
  origin.x = newValue.x - (size.width / 2)
  origin.y = newValue.y - (size.height / 2)
 }
 }
}

struct SomeStructure {
 static var storedTypeProperty = "Some value."
 static var computedTypeProperty: Int {
 // 这里返回一个 Int 值
 }
}

struct TimesTable {
 let multiplier: Int
 subscript(index: Int) -> Int {
  return multiplier * index
 }
}
let threeTimesTable = TimesTable(multiplier: 3)
println("3的6倍是\(threeTimesTable[6])")
// 输出 "3的6倍是18"

class Vehicle {
 var numberOfWheels: Int
 var maxPassengers: Int
 func description() -> String {
  return "\(numberOfWheels) wheels; up to \(maxPassengers) passengers"
 }
 init() {
  numberOfWheels = 0
  maxPassengers = 1
 }
}

class Bicycle: Vehicle {
 init() {
  super.init()
  numberOfWheels = 2
 }
}

class Car: Vehicle {
 var speed: Double = 0.0
 override var speed: Double {
 get {
  return super.speed
 }
 set {
  super.speed = min(newValue, 40.0)
 }
 }
 init() {
  super.init()
  maxPassengers = 5
  numberOfWheels = 4
 }
 override func description() -> String {
  return super.description() + "; "
   + "traveling at \(speed) mph"
 }
}

struct Celsius {
 var temperatureInCelsius: Double = 0.0
 init(fromFahrenheit fahrenheit: Double) {
  temperatureInCelsius = (fahrenheit - 32.0) / 1.8
 }
 init(fromKelvin kelvin: Double) {
  temperatureInCelsius = kelvin - 273.15
 }
}
 
let boilingPointOfWater = Celsius(fromFahrenheit: 212.0)
// boilingPointOfWater.temperatureInCelsius 是 100.0
let freezingPointOfWater = Celsius(fromKelvin: 273.15)
// freezingPointOfWater.temperatureInCelsius 是 0.0”

class Player {
 var coinsInPurse: Int
 init(coins: Int) {
  coinsInPurse = Bank.vendCoins(coins)
 }
 
 func winCoins(coins: Int) {
  coinsInPurse += Bank.vendCoins(coins)
 }
 
 deinit {
  Bank.receiveCoins(coinsInPurse)
 }
}
 
var player = Player(coins:200)
player = nil //调用deinit方法

class Player{
 var age:Int
}
 
extension Player{
 func repetitions(task: () -> ()) {
  for i in 0..self {
   task()
  }
 }
}

 protocol SomeProtocol {
  var mustBeSettable: Int { get set }
  var doesNotNeedToBeSettable: Int { get }
  func someTypeMethod()
 }

 protocol InheritingProtocol: SomeProtocol, AnotherProtocol {
  // protocol definition goes here
 }

 func swapTwoValues<T>(inout a: T, inout b: T) {
  let temporaryA = a
  a = b
  b = temporaryA
 }

struct Vector2D {
 var x = 0.0, y = 0.0
}
@infix func + (left: Vector2D, right: Vector2D) -> Vector2D {
 return Vector2D(x: left.x + right.x, y: left.y + right.y)
}

@prefix @assignment func ++ (inout vector: Vector2D) -> Vector2D {
 vector += Vector2D(x: 1.0, y: 1.0)
 return vector
}

operator prefix +++ {}
@prefix @assignment func +++ (inout vector: Vector2D) -> Vector2D {
 vector += vector
 return vector
}

operator infix +- { associativity left precedence 140 }
func +- (left: Vector2D, right: Vector2D) -> Vector2D {
 return Vector2D(x: left.x + right.x, y: left.y - right.y)
}
let firstVector = Vector2D(x: 1.0, y: 2.0)
let secondVector = Vector2D(x: 3.0, y: 4.0)
let plusMinusVector = firstVector +- secondVector
// plusMinusVector 此时的值为 (4.0, -2.0)