swift学习二:基本的语法
声明本文转载自:http://www.cocoachina.com/applenews/devnews/2014/0603/8653.html
Swift是什么?
Swift is a new programming language for iOS and OS X apps that 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 imagine how software development works.
Swift is the first industrial-quality systems programming language that is as expressive and enjoyable as a scripting language.
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- println("Hello, world")
- var myVariable = 42
- myVariable = 50
- let myConstant = 42
- let explicitDouble : Double = 70
- let label = "The width is "
- let width = 94
- let width = label + String(width)
- let apples = 3
- let oranges = 5
- let appleSummary = "I have \(apples) apples."
- let appleSummary = "I have \(apples + oranges) pieces of fruit."
- 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[]()
- let emptyDictionary = Dictionary<String, Float>()
- let individualScores = [75, 43, 103, 87, 12]
- var teamScore = 0
- for score in individualScores {
- if score > 50 {
- teamScore += 3
- } else {
- teamScore += 1
- }
- }
- var optionalString: String? = "Hello"
- optionalString == nil
- var optionalName: String? = "John Appleseed"
- var gretting = "Hello!"
- if let name = optionalName {
- gretting = "Hello, \(name)"
- }
- 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."
- }
- 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
- }
- }
- }
- largest
- var n = 2
- while n < 100 {
- n = n * 2
- }
- n
- var m = 2
- do {
- m = m * 2
- } while m < 100
- m
- var firstForLoop = 0
- for i in 0..3 {
- firstForLoop += i
- }
- firstForLoop
- var secondForLoop = 0
- for var i = 0; i < 3; ++i {
- secondForLoop += 1
- }
- secondForLoop
- func greet(name: String, day: String) -> String {
- return "Hello \(name), today is \(day)."
- }
- greet("Bob", "Tuesday")
- func getGasPrices() -> (Double, Double, Double) {
- return (3.59, 3.69, 3.79)
- }
- getGasPrices()
- func sumOf(numbers: Int...) -> Int {
- var sum = 0
- for number in numbers {
- sum += number
- }
- return sum
- }
- sumOf()
- sumOf(42, 597, 12)
- 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()
- 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, lessThanTen)
- numbers.map({
- (number: Int) -> Int in
- let result = 3 * number
- return result
- })
- numbers.map({ number in 3 * number })
- sort([1, 5, 3, 12, 2]) { $0 > $1 }
- class Shape {
- var numberOfSides = 0
- func simpleDescription() -> String {
- return "A shape with \(numberOfSides) sides."
- }
- }
- var shape = Shape()
- shape.numberOfSides = 7
- var shapeDescription = shape.simpleDescription()
- 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: 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()
- class EquilateralTriangle: NamedShape {
- var sideLength: Double = 0.0
- init(sideLength: Double, name: String) {
- self.sideLength = sideLength
- super.init(name: name)
- numberOfSides = 3
- }
- var perimeter: Double {
- get {
- return 3.0 * sideLength
- }
- set {
- sideLength = newValue / 3.0
- }
- }
- override func simpleDescription() -> String {
- return "An equilateral triagle with sides of length \(sideLength)."
- }
- }
- var triangle = EquilateralTriangle(sideLength: 3.1, name: "a triangle")
- triangle.perimeter
- triangle.perimeter = 9.9
- triangle.sideLength
- class TriangleAndSquare {
- var triangle: EquilateralTriangle {
- willSet {
- square.sideLength = newValue.sideLength
- }
- }
- var square: Square {
- willSet {
- triangle.sideLength = newValue.sideLength
- }
- }
- init(size: Double, name: String) {
- square = Square(sideLength: size, name: name)
- triangle = EquilateralTriangle(sideLength: size, name: name)
- }
- }
- var triangleAndSquare = TriangleAndSquare(size: 10, name: "another test shape")
- triangleAndSquare.square.sideLength
- triangleAndSquare.square = Square(sideLength: 50, name: "larger square")
- triangleAndSquare.triangle.sideLength
- class Counter {
- var count: Int = 0
- func incrementBy(amount: Int, numberOfTimes times: Int) {
- count += amount * times
- }
- }
- var counter = Counter()
- counter.incrementBy(2, numberOfTimes: 7)
- 1
- 2
- 3
- let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional
- square")
- let sideLength = optionalSquare?.sideLength
- 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()
- }
- enum Suit {
- case Spades, Hearts, Diamonds, Clubs
- func simpleDescription() -> String {
- switch self {
- case .Spades:
- return "spades"
- case .Hearts:
- return "hearts"
- case .Diamonds:
- return "diamonds"
- case .Clubs:
- return "clubs"
- }
- }
- }
- let hearts = Suit.Hearts
- let heartsDescription = hearts.simpleDescription()
- 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):
- let serverResponse = "Failure... \(error)"
- }
- 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()
- 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.simpleDescription
- struct SimpleStructure: ExampleProtocol {
- var simpleDescription: String = "A simple structure"
- mutating func adjust() {
- simpleDescription += " (adjusted)"
- }
- }
- var b = SimpleStructure()
- b.adjust()
- let bDescription = b.simpleDescription
- extension Int: ExampleProtocol {
- var simpleDescription: String {
- return "The number \(self)"
- }
- mutating func adjust() {
- self += 42
- }
- }
- 7.simpleDescription
- func repeat<ItemType>(item: ItemType, times: Int) -> ItemType[] {
- var result = ItemType[]()
- for i in 0..times {
- result += item
- }
- return result
- }
- repeat("knock", 4)
- // Reimplement the Swift standard library's optional type
- enum OptionalValue<T> {
- case None
- case Some(T)
- }
- var possibleInteger: OptionalValue<Int> = .None
- possibleInteger = .Some(100)
- func anyCommonElements <T, U where T: Sequence, U: Sequence, T.GeneratorType.Element: Equatable, T.GeneratorType.Element == U.GeneratorType.Element> (lhs: T, rhs: U) -> Bool {
- for lhsItem in lhs {
- for rhsItem in rhs {
- if lhsItem == rhsItem {
- return true
- }
- }
- }
- return false
- }
- anyCommonElements([1, 2, 3], [3])
转载于:https://www.cnblogs.com/bhlsheji/p/4297058.html
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