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")
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基础
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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
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数据类型
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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
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let possibleString: String? = "An optional string."
println(possibleString!)
let assumedString: String! = "An implicitly unwrapped optional string."
println(assumedString)
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数据流
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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")
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函数
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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 }
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对象和类
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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: , b: )
pair.a //
pair.b //
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
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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()