赶时髦过了一遍Swift 语言....

Swift 语言      2014年6月3日发布，替代OBJECT-C      Swift is a new programming language for creating iOS and OS X apps. Swift builds on the best of C and Objective-C, without the constraints of C compatibility. Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible, and more fun. Swift’s clean slate, backed by the mature and much-loved Cocoa and Cocoa Touch frameworks, is an opportunity to reimagine how software development works. 文档      https://itunes.apple.com/us/book/the-swift-programming-language/id881256329?mt=11      http://download.csdn.net/detail/surfsky/7440835  helloWorld    println("Hello, world")  -------------------------------------------------------------基础-------------------------------------------------------------注释    //    /**/ 分号    单行无需加分号    多个语句放在一行，需要加分号  变量    var myVariable = 42 常量    let myConstant = 42    let explicitDouble: Double = 70  -------------------------------------------------------------数据类型-------------------------------------------------------------数字类型    类型          Int: Int32, Int64          UInt: UInt32, Uint64          Double          Float    各种表示方法      let decimalInteger = 17      let binaryInteger = 0b10001 // 17 in binary notation      let octalInteger = 0o21 // 17 in octal notation      let hexadecimalInteger = 0x11 // 17 in hexadecimal notation      let decimalDouble = 12.1875      let exponentDouble = 1.21875e1      let hexadecimalDouble = 0xC.3p0      let paddedDouble = 000123.456      let oneMillion = 1_000_000 布尔（boolean）    let orangesAreOrange = true    let turnipsAreDelicious = false 向量    let (statusCode, statusMessage) = (404, "Not Found")    let (x, y) = (1, 2)    let http200Status = (statusCode: 200, description: "OK")    println("The status code is \(http200Status.statusCode)") 字符串    let label = "The width is "    let width = 94    let widthLabel = label + String(width)    字符串相加        let apples = 3        let oranges = 5        let appleSummary = "I have \(apples) apples."        let fruitSummary = "I have \(apples + oranges) pieces of fruit."数组    var shoppingList = ["catfish", "water", "tulips", "blue paint"]    shoppingList[1] = "bottle of water"    var occupations = ["Malcolm": "Captain", "Kaylee": "Mechanic",]    occupations["Jayne"] = "Public Relations"    let emptyArray = String[]()    shoppingList = [] 字典    let emptyDictionary = Dictionary<String, Float>()    emptyDictionary = [:]  空（nil）和可为空对象    var serverResponseCode: Int? = 404    serverResponseCode = nil    ----------------------------------------------        let possibleString: String? = "An optional string."    println(possibleString!)    let assumedString: String! = "An implicitly unwrapped optional string."    println(assumedString)            -------------------------------------------------------------数据流-------------------------------------------------------------if    if i == 1 {        // this example will compile successfully    }  switch    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."    }  for    var firstForLoop = 0    for var i = 0; i < 3; ++i {        firstForLoop += 1    }    for i in 0..3 {        firstForLoop += i    }  for(遍历数组)    let individualScores = [75, 43, 103, 87, 12]    var teamScore = 0    for score in individualScores {        if score > 50 {            teamScore += 3        } else {            teamScore += 1        }    }     for(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            }        }    }   while    var n = 2    while n < 100 {        n = n * 2    } do...while    var m = 2    do {        m = m * 2    } while m < 100          断言（assert）    let age = -3    assert(age >= 0, "A person's age cannot be less than zero")      -------------------------------------------------------------函数-------------------------------------------------------------函数定义和调用    func greet(name: String, day: String) -> String {        return "Hello \(name), today is \(day)."    }    greet("Bob", "Tuesday")  返回多个数据    func getGasPrices() -> (Double, Double, Double) {        return (3.59, 3.69, 3.79)    }    getGasPrices() 不限个数参数    func sumOf(numbers: Int...) -> Int {        var sum = 0        for number in numbers {            sum += number        }        return sum    }    sumOf()    sumOf(42, 597, 12)  嵌套函数    func returnFifteen() -> Int {        var y = 10        func add() {            y += 5        }        add()        return y    }    returnFifteen()  返回函数变量    func makeIncrementer() -> (Int -> Int) {        func addOne(number: Int) -> Int {            return 1 + number        }        return addOne    }    var increment = makeIncrementer()    increment(7) 函数作为输入参数（类似lambda表达式）    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, lessThanTen) 闭包    numbers.map({        (number: Int) -> Int in        let result = 3 * number        return result    }) 用编号替代名字    sort([1, 5, 3, 12, 2]) { $0 > $1 }  -------------------------------------------------------------对象和类-------------------------------------------------------------类定义    class Shape {        var numberOfSides: Int = 0        var name: String        init(name: String) {            self.name = name        }        func simpleDescription() -> String {            return "A shape with \(numberOfSides) sides."        }    } 使用    var shape = Shape()    shape.numberOfSides = 7    var shapeDescription = shape.simpleDescription()  self/super    self  -> this    super -> parent      继承    class Square: NamedShape {        var sideLength: Double        init(sideLength: Double, name: String) {            self.sideLength = sideLength            super.init(name: name)            numberOfSides = 4        }        func area() -> Double {            return sideLength * sideLength        }        override func simpleDescription() -> String {            return "A square with sides of length \(sideLength)."        }    }    let test = Square(sideLength: 5.2, name: "my test square")    test.area()    test.simpleDescription() 属性    var perimeter: Double {        get {return 3.0 * sideLength}        set {sideLength = newValue / 3.0}    }  方法重载    override func simpleDescription() -> String {        return "An equilateral triagle with sides of length \(sideLength)."    } willSet和didSet（属性的值设置前后处理）    var triangle: EquilateralTriangle {        willSet {            square.sideLength = newValue.sideLength        }    } 可为空对象方法调用    let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional square")    let sideLength = optionalSquare?.sideLength   -------------------------------------------------------------枚举和结构体-------------------------------------------------------------枚举    enum Rank: Int {        case Ace = 1        case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten        case Jack, Queen, King             func simpleDescription() -> String {            switch self {                case .Ace:                                        return "ace"                              case .Jack:                                     return "jack"                               case .Queen:                                      return "queen"                              case .King:                                       return "king"                               default:                                          return String(self.toRaw())              }        }    }    let ace = Rank.Ace               let aceRawValue = ace.toRaw()    if let convertedRank = Rank.fromRaw(3) {        let threeDescription = convertedRank.simpleDescription()    }  看得有点晕    enum ServerResponse {        case Result(String, String)        case Error(String)    }    let success = ServerResponse.Result("6:00 am", "8:09 pm")    let failure = ServerResponse.Error("Out of cheese.")         switch success {        case let .Result(sunrise, sunset):        let serverResponse = "Sunrise is at \(sunrise) and sunset is at \(sunset)."        case let .Error(error):    }  结构体    struct Card {        var rank: Rank        var suit: Suit        func simpleDescription() -> String {            return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"        }    }    let threeOfSpades = Card(rank: .Three, suit: .Spades)    let threeOfSpadesDescription = threeOfSpades.simpleDescription()