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.youkuaiyun.com/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   泛型

struct Pair<T: Equatable> {
    let a: T!
    let b: T!
    init(a: T, b: T) {
        self.a = a
        self.b = b
    }
    func equal() -> Bool {
        return a == b
    }
}

let pair = Pair(a: 5, b: 10)
pair.a // 5
pair.b // 10
pair.equal() // false
 

let floatPair = Pair(a: 3.14159, b: 2.0)
floatPair.a // 3.14159
floatPair.b // 2.0
floatPair.equal() // false

 

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------------------------------------------------------------- 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()