Apple官方開發手冊地址：

https://developer.apple.com/library/prerelease/ios/referencelibrary/GettingStarted/LandingPage/index.html

語法概覽

1 Simple Values

常量定義：let

變量定義：var

常量或變量類型和初始值一致：var myVariable = 42myVariable = 50let myConstant = 42也能夠顯式的指定類型： let explicitDouble:Double = 70

類型轉換，比方String()：

let label = "The width is "let width = 94let widthLabel = label + String(width)
打印常量/變量值使用 \()

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

創建數組或字典。使用[ ]：

var shoppingList = ["catfish", "water", "tulips", "blue paint"]shoppingList[1] = "bottle of water"var occupations = ["Malcolm": "Captain","Kaylee": "Mechanic",]occupations["Jayne"] = "Public Relations"初始化一個空的數組或字典：

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

條件推斷 if / switch

循環控制 for-in for? while? do-while

let individualScores = [75, 43, 103, 87, 12]var teamScore = 0for score in individualScores {if score > 50 {teamScore += 3} else {teamScore += 1}}teamScore

switch case

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-in

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

var m = 2 do { m = m * 2 } while m < 100 m

for?

傳統格式： var secondForLoop = 0 for var i = 0; i < 3; ++i { secondForLoop += 1 } secondForLoop

新的格式： var firstForLoop = 0 for i in 0..3 { firstForLoop += i } firstForLoop
3 Functions and Closures

函數名(參數1，參數2)->返回類型func greet(name: String, day: String) -> String {return "Hello \(name), today is \(day)."}greet("Bob", "Tuesday")

返回多個參數：

func getGasPrices() -> (Double, Double, Double) {return (3.59, 3.69, 3.79)}getGasPrices()
可變參數：

func sumOf(numbers: Int...) -> Int {var sum = 0for number in numbers {sum += number}return sum}sumOf()sumOf(42, 597, 12)函數嵌套：

func returnFifteen() -> Int {var y = 10func add() {y += 5}add()return y}returnFifteen()返回嵌套函數返回值：

func makeIncrementer() -> (Int -> Int) {func addOne(number: Int) -> Int {return 1 + number}return addOne}var increment = makeIncrementer()increment(7)<pre name="code" class="objc"> class NamedShape {var numberOfSides: Int = 0var name: Stringinit(name: String) {self.name = name}func simpleDescription() -> String {return "A shape with \(numberOfSides) sides."}}
用還有一個函數作參數：

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)
{}和$的使用

numbers.map({ number in 3 * number })
sort([1, 5, 3, 12, 2]) { $0 > $1 }

4 Objects and Classes

類實現.構造和析構函數 init/deinit

class NamedShape {var numberOfSides: Int = 0var name: Stringinit(name: String) {self.name = name}<code class="code-voice">deinit</code>(){}func simpleDescription() -> String {return "A shape with \(numberOfSides) sides."}}類使用:

var shape = Shape()shape.numberOfSides = 7var shapeDescription = shape.simpleDescription()

類的繼承和函數重載：

<pre name="code" class="objc">class EquilateralTriangle: NamedShape {var sideLength: Double = 0.0子類中初始化須要運行：1）設置子類屬性值2）父類初始化3）設置父類屬性值init(sideLength: Double, name: String) {self.sideLength = sideLengthsuper.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)."} }
預設置 willSet和 didSet
willSet { square.sideLength = newValue.sideLength }
When working with optional values, you can write ? before operations like methods, properties, and subscripting. If the value before the ? is nil, everything after the ?

is ignored and the value of the whole expression is nil. Otherwise, the optional value is unwrapped, and everything after the ?

acts on the unwrapped value. In both cases, the value of the whole expression is an optional value.

let optionalSquare: Square? = Square(sideLength: 2.5, name: "optional square")let sideLength = optionalSquare?.sideLength

5 Enumerations and Structures

enum的定義和使用

enum Rank: Int {case Ace = 1case Two, Three, Four, Five, Six, Seven, Eight, Nine, Tencase Jack, Queen, Kingfunc 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.Acelet aceRawValue = ace.toRaw()enum值和raw值的轉換（toRaw和fromRaw）

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

struct 和class的差別：

struct使用的時候是拷貝。class使用的時候是引用。

6 Protocols and Extensions

聲明一個protocol

protocol ExampleProtocol {var simpleDescription: String { get }mutating func adjust()}

協議使用：

class SimpleClass: ExampleProtocol {var simpleDescription: String = "A very simple class."var anotherProperty: Int = 69105func 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

Notice the use of the mutating keyword in the declaration of SimpleStructure to mark a method that modifies the structure.

Use extension to add functionality to an existing type

extension Int: ExampleProtocol {var simpleDescription: String {return "The number \(self)"}mutating func adjust() {self += 42}}simpleDescription

7? Generics

參數類型待定：

func repeat<ItemType>(item: ItemType, times: Int) -> ItemType[] {var result = ItemType[]()for i in 0..times {result += item}return result}repeat("knock", 4)使用where帶參數列表：

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])

轉載于:https://www.cnblogs.com/mfmdaoyou/p/7348719.html

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