let 聲明常量，var 聲明變量：

var myVar = 42
let myConstant =30

明確聲明類型：
var var1:Int;
拼接字符串：
let apples = 3; let fruit = "i have \(apples) apples"
統(tǒng)一[] 創(chuàng)建數(shù)組和字典；

      var array = ["heloo", "water"]
        array[1] = "friuit"
        var dict = ["key1":"value1",
            "key2":"value2"]
        dict["key1"] = "vlue3"

創(chuàng)建空數(shù)組和字典：

        let empArray = [String]()
        let empDict = [String:Float]()   

類型后面加一個(gè)問號來標(biāo)記這個(gè)變量的值是可選的。
var optionStr:String? = "hello"

switch支持任意類型的數(shù)據(jù)以及各種比較操作——不僅僅是整數(shù)以及測試相等。
if ,for ,switch 后面跟{}

  switch vagetabl
        {
            case "calle":
             print("call")
            case "hello","hello2":
             println("ok sog")
            case let x where x.hasSuffix("pepper"):
            println("write songs")
            default:
            println("nothing")
        }

switch 不需要break語句；
for-in來遍歷字典

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
       } 
  }
}
  for i in 0...5
   {
      //使用..<創(chuàng)建的范圍不包含上界，如果想包含的話需要使用...
   }
    var i = 0
    while i<20
    {
    }

函數(shù)聲明：
使用func來聲明一個(gè)函數(shù)，使用名字和參數(shù)來調(diào)用函數(shù)。使用->來指定函數(shù)返回值。函數(shù)可以嵌套，可以當(dāng)做返回值返回，也可以做為參數(shù)傳入；

func returnFifteen() -> Int {
  var y = 10 
   func add() { 
      y += 5 
  } 
  add() 
  return y
 }
returnFifteen()

func makeIncrementer() -> (Int -> Int)
 {
   func addOne(number: Int) -> Int
     {
     return 1 + number 
     }
     return addOne
}
   var increment = makeIncrementer()

調(diào)用 increment(7)

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, 7, 12]
  hasAnyMatches(numbers,condition: lessThanTen)

入?yún)⒙暶鳎?conditon:Int -> Bool

函數(shù)實(shí)際是特殊的閉包，可用{}來創(chuàng)建匿名閉包；

numbers.map({
   (number: Int) -> Int in
       let result = 3 * number
    return result
})

類，使用class聲明;每個(gè)屬性都需要賦值——無論是通過聲明（就像numberOfSides）還是通過構(gòu)造器（就像name）。

class NamedShape
 {
    var numberOfSides: Int = 0
    var name: String
    init(name: String) 
   { 
       self.name = name
   } 
    func simpleDescription() -> String 
   { 
      return "A shape with \(numberOfSides) sides." 
  }
}

class Square : NameShape
{
    var sideLength:Double = 0.0
    init(sideLength:Double,name:String)
    {
        self.sideLength = sideLength;
        super.init(name: name)
        numberOfSlides = 4;
    }
    
    var perimeter:Double
    {
        get
        {
            return 3.0 * sideLength;
        }
        
        set
        {
            sideLength = newValue / 3.0;
        }
      willSet
     {
      triangle.sideLength = newValue.sideLength
      }
      didSet
      {
      triangle.sideLength = newValue.sideLength
      }
    }
    
    func area() -> Double
    {
        return sideLength * sideLength;
    }
    override func simpleDescription() -> NSString {
        return "A square sides of length \(sideLength)."
    }
}

類中方法調(diào)用和普通函數(shù)區(qū)別：
函數(shù)的參數(shù)名只在函數(shù)內(nèi)部使用，但是方法的參數(shù)名需要在調(diào)用的時(shí)候顯式說明（除了第一個(gè)參數(shù)）。默認(rèn)情況下，方法的參數(shù)名和它在方法內(nèi)部的名字一樣，不過你也可以定義第二個(gè)名字，這個(gè)名字被用在方法內(nèi)部。

 class Counter 
  { 
      var count: Int = 0
     func incrementBy(amount: Int, numberOfTimes times: Int) 
{ 
     count += amount * times
  }
}
var counter = Counter()counter.incrementBy(2, numberOfTimes: 7)

類，枚舉，結(jié)構(gòu)體都可以實(shí)現(xiàn)協(xié)議；

使用protocol
來聲明一個(gè)協(xié)議。
protocol ExampleProtocol {
 var simpleDescription: String { get } 
 mutating func adjust()
}

class SimpleClass: ExampleProtocol 
{
    var simpleDescription: String = "A very simple class." 
    var anotherProperty: Int = 69105
    func adjust()
   {
    simpleDescription += " Now 100% adjusted."    
   }
}
var a = SimpleClass()
a.adjust()
let aDescription = a.simpleDescriptionstruct 
SimpleStructure: ExampleProtocol 
{
   var simpleDescription: String = "A simple structure" 
    mutating func adjust() 
  { 
     simpleDescription += " (adjusted)"  
  }
}
  var b = SimpleStructure()
  b.adjust()
  let bDescription = b.simpleDescription

注意聲明SimpleStructure時(shí)候mutating關(guān)鍵字用來標(biāo)記一個(gè)會修改結(jié)構(gòu)體的方法。SimpleClass的聲明不需要標(biāo)記任何方法因?yàn)轭愔械姆椒ń?jīng)常會修改類。

使用extension來為現(xiàn)有的類型添加功能，比如新的方法和參數(shù)

extension Int:ExamplePro
{
    var simDes:String
    {
        return "the number \(self)"
    }
    mutating func adjust() {
        self += 42
    }
}
        println(7.simDes)

在尖括號里寫一個(gè)名字來創(chuàng)建一個(gè)泛型函數(shù)或者類型

 func repeatIem<Item>(item:Item,numberOfTime:Int) ->[Item]
        {
            var result = [Item]()
            for _ in 0..<numberOfTime
            {
                result.append(item)
            }
            return result
        }
        repeatIem("kenow", numberOfTime:4 )
        

http://numbbbbb.gitbooks.io/-the-swift-programming-language-/content/chapter1/02_a_swift_tour.html
http://www.cocoachina.com/bbs/read.php?tid-206201.html
http://www.cocoachina.com/bbs/read.php?tid-205308.html
http://www.cocoachina.com/bbs/read.php?tid-204512.html
參考 http://www.cocoachina.com/bbs/thread.php?fid=57