Swift编程语言简介

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这篇文章简要介绍了苹果于WWDC 2014发布的编程语言Swift。 

1. 

   println("Hello, world") 

   

1. 

   var myVariable = 42 
   myVariable = 50 
   let myConstant = 42 

   

1. 

   let explicitDouble : Double = 70 

   

1. 

   let label = "The width is " 
   let width = 94 
   let width = label + String(width) 

   

1. 

   let apples = 3 
   let oranges = 5 
   let appleSummary = "I have \(apples) apples." 
   let appleSummary = "I have \(apples + oranges) pieces of fruit." 

   

1. 

   var shoppingList = ["catfish", "water", "tulips", "blue paint"] 
   shoppingList[1] = "bottle of water" 
     
   var occupations = [ 
       "Malcolm": "Captain", 
       "Kaylee": "Mechanic", 
   ] 
   occupations["Jayne"] = "Public Relations" 

   

1. 

   1 let emptyArray = String[]() 
   2 let emptyDictionary = Dictionary<String, Float>() 

   

1. 

   1 let individualScores = [75, 43, 103, 87, 12] 
   2 var teamScore = 0 
   3 for score in individualScores { 
   4     if score > 50 { 
   5         teamScore += 3 
   6     } else { 
   7         teamScore += 1 
   8     } 
   9 } 

   

    

1. 

   var optionalString: String? = "Hello" 
   optionalString == nil 
     
   var optionalName: String? = "John Appleseed" 
   var gretting = "Hello!" 
   if let name = optionalName { 
       gretting = "Hello, \(name)" 
   } 

   

1. 

    1 let vegetable = "red pepper" 
    2 switch vegetable { 
    3 case "celery": 
    4     let vegetableComment = "Add some raisins and make ants on a log." 
    5 case "cucumber", "watercress": 
    6     let vegetableComment = "That would make a good tea sandwich." 
    7 case let x where x.hasSuffix("pepper"): 
    8     let vegetableComment = "Is it a spicy \(x)?" 
    9 default: 
   10     let vegetableComment = "Everything tastes good in soup." 
   11 } 

   

1. 

    1 let interestingNumbers = [ 
    2     "Prime": [2, 3, 5, 7, 11, 13], 
    3     "Fibonacci": [1, 1, 2, 3, 5, 8], 
    4     "Square": [1, 4, 9, 16, 25], 
    5 ] 
    6 var largest = 0 
    7 for (kind, numbers) in interestingNumbers { 
    8     for number in numbers { 
    9         if number > largest { 
   10             largest = number 
   11         } 
   12     } 
   13 } 
   14 largest 

   

    

1. 

    1 var n = 2 
    2 while n < 100 { 
    3     n = n * 2 
    4 } 
    5 n 
    6   
    7 var m = 2 
    8 do { 
    9     m = m * 2 
   10 } while m < 100 
   11 m 

   

    

1. 

    1 var firstForLoop = 0 
    2 for i in 0..3 { 
    3     firstForLoop += i 
    4 } 
    5 firstForLoop 
    6   
    7 var secondForLoop = 0 
    8 for var i = 0; i < 3; ++i { 
    9     secondForLoop += 1 
   10 } 
   11 secondForLoop 

   

1. 

   func greet(name: String, day: String) -> String { 
       return "Hello \(name), today is \(day)." 
   } 
   greet("Bob", "Tuesday") 

   

    

1. 

   1 func getGasPrices() -> (Double, Double, Double) { 
   2     return (3.59, 3.69, 3.79) 
   3 } 
   4 getGasPrices() 

   

    

1. 

   1 func sumOf(numbers: Int...) -> Int { 
   2     var sum = 0 
   3     for number in numbers { 
   4         sum += number 
   5     } 
   6     return sum 
   7 } 
   8 sumOf() 
   9 sumOf(42, 597, 12) 

   

    

1. 

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

   

    

1. 

   1 func makeIncrementer() -> (Int -> Int) { 
   2     func addOne(number: Int) -> Int { 
   3         return 1 + number 
   4     } 
   5     return addOne 
   6 } 
   7 var increment = makeIncrementer() 
   8 increment(7) 

   

    

1. 

    1 func hasAnyMatches(list: Int[], condition: Int -> Bool) -> Bool { 
    2     for item in list { 
    3         if condition(item) { 
    4             return true 
    5         } 
    6     } 
    7     return false 
    8 } 
    9 func lessThanTen(number: Int) -> Bool { 
   10     return number < 10 
   11 } 
   12 var numbers = [20, 19, 7, 12] 
   13 hasAnyMatches(numbers, lessThanTen) 

   

    

1. 

   1 numbers.map({ 
   2     (number: Int) -> Int in 
   3     let result = 3 * number 
   4     return result 
   5     }) 

   

    

1. 

   1 numbers.map({ number in 3 * number }) 

   

    

1. 

   1 sort([1, 5, 3, 12, 2]) { $0 > $1 } 

   

    

1. 

   1 class Shape { 
   2     var numberOfSides = 0 
   3     func simpleDescription() -> String { 
   4         return "A shape with \(numberOfSides) sides." 
   5     } 
   6 } 

   

    

　　

1 var shape = Shape() 
2 shape.numberOfSides = 7 
3 var shapeDescription = shape.simpleDescription() 

 

1. 

    1 class NamedShape { 
    2     var numberOfSides: Int = 0 
    3     var name: String 
    4   
    5     init(name: String) { 
    6         self.name = name 
    7     } 
    8   
    9     func simpleDescription() -> String { 
   10         return "A shape with \(numberOfSides) sides." 
   11     } 
   12 } 

   

    

1. 

    1 class Square: NamedShape { 
    2     var sideLength: Double 
    3   
    4     init(sideLength: Double, name: String) { 
    5         self.sideLength = sideLength 
    6         super.init(name: name) 
    7         numberOfSides = 4 
    8     } 
    9   
   10     func area() -> Double { 
   11         return sideLength * sideLength 
   12     } 
   13   
   14     override func simpleDescription() -> String { 
   15         return "A square with sides of length \(sideLength)." 
   16     } 
   17 } 
   18 let test = Square(sideLength: 5.2, name: "my test square") 
   19 test.area() 
   20 test.simpleDescription() 

   

    

1. 

    1 class EquilateralTriangle: NamedShape { 
    2     var sideLength: Double = 0.0 
    3  
    4     init(sideLength: Double, name: String) { 
    5         self.sideLength = sideLength 
    6         super.init(name: name) 
    7         numberOfSides = 3 
    8     } 
    9  
   10     var perimeter: Double { 
   11     get { 
   12         return 3.0 * sideLength 
   13     } 
   14     set { 
   15         sideLength = newValue / 3.0 
   16     } 
   17     } 
   18  
   19     override func simpleDescription() -> String { 
   20         return "An equilateral triagle with sides of length \(sideLength)." 
   21     } 
   22 } 
   23 var triangle = EquilateralTriangle(sideLength: 3.1, name: "a triangle") 
   24 triangle.perimeter 
   25 triangle.perimeter = 9.9 
   26 triangle.sideLength 

   

    

1. 

    1 class TriangleAndSquare { 
    2     var triangle: EquilateralTriangle { 
    3     willSet { 
    4         square.sideLength = newValue.sideLength 
    5     } 
    6     } 
    7     var square: Square { 
    8     willSet { 
    9         triangle.sideLength = newValue.sideLength 
   10     } 
   11     } 
   12     init(size: Double, name: String) { 
   13         square = Square(sideLength: size, name: name) 
   14         triangle = EquilateralTriangle(sideLength: size, name: name) 
   15     } 
   16 } 
   17 var triangleAndSquare = TriangleAndSquare(size: 10, name: "another test shape") 
   18 triangleAndSquare.square.sideLength 
   19 triangleAndSquare.square = Square(sideLength: 50, name: "larger square") 
   20 triangleAndSquare.triangle.sideLength 

   

    

1. 

   1 class Counter { 
   2     var count: Int = 0 
   3     func incrementBy(amount: Int, numberOfTimes times: Int) { 
   4         count += amount * times 
   5     } 
   6 } 
   7 var counter = Counter() 
   8 counter.incrementBy(2, numberOfTimes: 7) 

   

    

1. 

   1 1 
   2 2 
   3 3 
   4 let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional  
   5 square") 
   6 let sideLength = optionalSquare?.sideLength 

   

    

1. 

    1 enum Rank: Int { 
    2     case Ace = 1 
    3     case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten 
    4     case Jack, Queen, King 
    5         func simpleDescription() -> String { 
    6         switch self { 
    7             case .Ace: 
    8                 return "ace" 
    9             case .Jack: 
   10                 return "jack" 
   11             case .Queen: 
   12                 return "queen" 
   13             case .King: 
   14                 return "king" 
   15             default: 
   16                 return String(self.toRaw()) 
   17         } 
   18     } 
   19 } 
   20 let ace = Rank.Ace 
   21 let aceRawValue = ace.toRaw() 

   

    

1. 

   1 if let convertedRank = Rank.fromRaw(3) { 
   2     let threeDescription = convertedRank.simpleDescription() 
   3 } 

   

    

1. 

    1 enum Suit { 
    2     case Spades, Hearts, Diamonds, Clubs 
    3         func simpleDescription() -> String { 
    4         switch self { 
    5             case .Spades: 
    6                 return "spades" 
    7             case .Hearts: 
    8                 return "hearts" 
    9             case .Diamonds: 
   10                 return "diamonds" 
   11             case .Clubs: 
   12                 return "clubs" 
   13         } 
   14     } 
   15 } 
   16 let hearts = Suit.Hearts 
   17 let heartsDescription = hearts.simpleDescription() 

   

    

1. 

    1 enum ServerResponse { 
    2     case Result(String, String) 
    3     case Error(String) 
    4 } 
    5   
    6 let success = ServerResponse.Result("6:00 am", "8:09 pm") 
    7 let failure = ServerResponse.Error("Out of cheese.") 
    8   
    9 switch success { 
   10     case let .Result(sunrise, sunset): 
   11         let serverResponse = "Sunrise is at \(sunrise) and sunset is at \(sunset)." 
   12     case let .Error(error): 
   13         let serverResponse = "Failure... \(error)" 
   14 } 

   

    

1. 

   1 struct Card { 
   2     var rank: Rank 
   3     var suit: Suit 
   4     func simpleDescription() -> String { 
   5         return "The \(rank.simpleDescription()) of \(suit.simpleDescription())" 
   6     } 
   7 } 
   8 let threeOfSpades = Card(rank: .Three, suit: .Spades) 
   9 let threeOfSpadesDescription = threeOfSpades.simpleDescription() 

   

    

1. 

   1 protocol ExampleProtocol { 
   2     var simpleDescription: String { get } 
   3     mutating func adjust() 
   4 } 

   

    

1. c
   

    1 lass SimpleClass: ExampleProtocol { 
    2     var simpleDescription: String = "A very simple class." 
    3     var anotherProperty: Int = 69105 
    4     func adjust() { 
    5         simpleDescription += " Now 100% adjusted." 
    6     } 
    7 } 
    8 var a = SimpleClass() 
    9 a.adjust() 
   10 let aDescription = a.simpleDescription 
   11   
   12 struct SimpleStructure: ExampleProtocol { 
   13     var simpleDescription: String = "A simple structure" 
   14     mutating func adjust() { 
   15         simpleDescription += " (adjusted)" 
   16     } 
   17 } 
   18 var b = SimpleStructure() 
   19 b.adjust() 
   20 let bDescription = b.simpleDescription 

   

1. 

   1 extension Int: ExampleProtocol { 
   2     var simpleDescription: String { 
   3         return "The number \(self)" 
   4     } 
   5     mutating func adjust() { 
   6         self += 42 
   7     } 
   8 } 
   9 7.simpleDescription 

   

1. 

   

   1 func repeat<ItemType>(item: ItemType, times: Int) -> ItemType[] { 
   2     var result = ItemType[]() 
   3     for i in 0..times { 
   4         result += item 
   5     } 
   6     return result 
   7 } 
   8 repeat("knock", 4) 

   

    

   

    

1. 

   1 // Reimplement the Swift standard library‘s optional type 
   2 enum OptionalValue<T> { 
   3     case None 
   4     case Some(T) 
   5 } 
   6 var possibleInteger: OptionalValue<Int> = .None 
   7 possibleInteger = .Some(100) 

   

    

1. 

    1 func anyCommonElements <T, U where T: Sequence, U: Sequence, T.GeneratorType.Element: Equatable, T.GeneratorType.Element == U.GeneratorType.Element> (lhs: T, rhs: U) -> Bool { 
    2     for lhsItem in lhs { 
    3         for rhsItem in rhs { 
    4             if lhsItem == rhsItem { 
    5                 return true 
    6             } 
    7         } 
    8     } 
    9     return false 
   10 } 
   11 anyCommonElements([1, 2, 3], [3]) 

   

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Swift编程语言简介

标签：des   c   style   class   blog   code   

原文地址：http://www.cnblogs.com/lkvt/p/3765951.html