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println() depreciated in swift2.0
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CY Lim
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@ -19,7 +19,7 @@ Swift 的官方语言教程 [Swift Programming Language](https://itunes.apple.co
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// 导入外部模块
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import UIKit
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//
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//
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// MARK: 基础
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//
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@ -28,12 +28,12 @@ import UIKit
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// TODO: TODO 标记
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// FIXME: FIXME 标记
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println("Hello, world")
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print("Hello, world")
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// 变量 (var) 的值设置后可以随意改变
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// 常量 (let) 的值设置后不能改变
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var myVariable = 42
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let øπΩ = "value" // 可以支持 unicode 变量名
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let øπΩ = "value" // 可以支持 unicode 变量名
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let π = 3.1415926
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let myConstant = 3.1415926
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let explicitDouble: Double = 70 // 明确指定变量类型为 Double ，否则编译器将自动推断变量类型
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@ -46,16 +46,16 @@ let piText = "Pi = \(π), Pi 2 = \(π * 2)" // 格式化字符串
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// 条件编译
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// 使用 -D 定义编译开关
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#if false
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println("Not printed")
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print("Not printed")
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let buildValue = 3
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#else
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let buildValue = 7
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#endif
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println("Build value: \(buildValue)") // Build value: 7
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print("Build value: \(buildValue)") // Build value: 7
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/*
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Optionals 是 Swift 的新特性，它允许你存储两种状态的值给 Optional 变量：有效值或 None
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Swift 要求所有的 Optinal 属性都必须有明确的值，如果为空，则必须明确设定为 nil
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Optional<T> 是个枚举类型
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@ -67,9 +67,9 @@ var someOptionalString2: Optional<String> = "optional"
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if someOptionalString != nil {
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// 变量不为空
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if someOptionalString!.hasPrefix("opt") {
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println("has the prefix")
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print("has the prefix")
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}
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let empty = someOptionalString?.isEmpty
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}
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someOptionalString = nil
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@ -94,7 +94,7 @@ anyObjectVar = "Changed value to a string, not good practice, but possible."
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/*
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这里是注释
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/*
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支持嵌套的注释
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*/
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@ -136,21 +136,21 @@ var emptyMutableDictionary = [String: Float]() // 使用 var 定义字典变量
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let myArray = [1, 1, 2, 3, 5]
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for value in myArray {
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if value == 1 {
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println("One!")
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print("One!")
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} else {
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println("Not one!")
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print("Not one!")
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}
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}
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// 字典的 for 循环
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var dict = ["one": 1, "two": 2]
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for (key, value) in dict {
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println("\(key): \(value)")
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print("\(key): \(value)")
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}
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// 区间的 loop 循环：其中 `...` 表示闭环区间，即[-1, 3]；`..<` 表示半开闭区间，即[-1,3)
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for i in -1...shoppingList.count {
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println(i)
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print(i)
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}
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shoppingList[1...2] = ["steak", "peacons"]
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// 可以使用 `..<` 来去掉最后一个元素
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@ -163,7 +163,7 @@ while i < 1000 {
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// do-while 循环
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do {
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println("hello")
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print("hello")
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} while 1 == 2
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// Switch 语句
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@ -177,7 +177,7 @@ case "cucumber", "watercress":
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let vegetableComment = "That would make a good tea sandwich."
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case let localScopeValue where localScopeValue.hasSuffix("pepper"):
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let vegetableComment = "Is it a spicy \(localScopeValue)?"
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default: // 在 Swift 里，switch 语句的 case 必须处理所有可能的情况，如果 case 无法全部处理，则必须包含 default语句
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default: // 在 Swift 里，switch 语句的 case 必须处理所有可能的情况，如果 case 无法全部处理，则必须包含 default语句
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let vegetableComment = "Everything tastes good in soup."
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}
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@ -219,8 +219,8 @@ let pricesTuple = getGasPrices()
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let price = pricesTuple.2 // 3.79
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// 通过下划线 (_) 来忽略不关心的值
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let (_, price1, _) = pricesTuple // price1 == 3.69
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println(price1 == pricesTuple.1) // true
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println("Gas price: \(price)")
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print(price1 == pricesTuple.1) // true
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print("Gas price: \(price)")
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// 可变参数
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func setup(numbers: Int...) {
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@ -248,7 +248,7 @@ func swapTwoInts(inout a: Int, inout b: Int) {
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var someIntA = 7
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var someIntB = 3
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swapTwoInts(&someIntA, &someIntB)
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println(someIntB) // 7
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print(someIntB) // 7
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//
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@ -296,7 +296,7 @@ print(numbers) // [3, 6, 18]
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struct NamesTable {
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let names = [String]()
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// 自定义下标运算符
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subscript(index: Int) -> String {
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return names[index]
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@ -306,7 +306,7 @@ struct NamesTable {
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// 结构体有一个自动生成的隐含的命名构造函数
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let namesTable = NamesTable(names: ["Me", "Them"])
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let name = namesTable[1]
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println("Name is \(name)") // Name is Them
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print("Name is \(name)") // Name is Them
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//
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// MARK: 类
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@ -329,7 +329,7 @@ public class Shape {
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internal class Rect: Shape {
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// 值属性 (Stored properties)
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var sideLength: Int = 1
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// 计算属性 (Computed properties)
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private var perimeter: Int {
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get {
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@ -340,11 +340,11 @@ internal class Rect: Shape {
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sideLength = newValue / 4
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}
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}
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// 延时加载的属性，只有这个属性第一次被引用时才进行初始化，而不是定义时就初始化
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// subShape 值为 nil ，直到 subShape 第一次被引用时才初始化为一个 Rect 实例
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lazy var subShape = Rect(sideLength: 4)
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// 监控属性值的变化。
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// 当我们需要在属性值改变时做一些事情，可以使用 `willSet` 和 `didSet` 来设置监控函数
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// `willSet`: 值改变之前被调用
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@ -352,14 +352,14 @@ internal class Rect: Shape {
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var identifier: String = "defaultID" {
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// `willSet` 的参数是即将设置的新值，参数名可以指定，如果没有指定，就是 `newValue`
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willSet(someIdentifier) {
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println(someIdentifier)
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print(someIdentifier)
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}
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// `didSet` 的参数是已经被覆盖掉的旧的值，参数名也可以指定，如果没有指定，就是 `oldValue`
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didSet {
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println(oldValue)
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print(oldValue)
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}
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}
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// 命名构造函数 (designated inits)，它必须初始化所有的成员变量，
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// 然后调用父类的命名构造函数继续初始化父类的所有变量。
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init(sideLength: Int) {
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@ -367,13 +367,13 @@ internal class Rect: Shape {
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// 必须显式地在构造函数最后调用父类的构造函数 super.init
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super.init()
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}
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func shrink() {
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if sideLength > 0 {
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--sideLength
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}
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}
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// 函数重载使用 override 关键字
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override func getArea() -> Int {
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return sideLength * sideLength
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@ -394,16 +394,16 @@ class Square: Rect {
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}
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var mySquare = Square()
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println(mySquare.getArea()) // 25
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print(mySquare.getArea()) // 25
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mySquare.shrink()
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println(mySquare.sideLength) // 4
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print(mySquare.sideLength) // 4
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// 类型转换
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let aShape = mySquare as Shape
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// 使用三个等号来比较是不是同一个实例
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if mySquare === aShape {
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println("Yep, it's mySquare")
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print("Yep, it's mySquare")
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}
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class Circle: Shape {
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@ -411,12 +411,12 @@ class Circle: Shape {
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override func getArea() -> Int {
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return 3 * radius * radius
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}
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// optional 构造函数，可能会返回 nil
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init?(radius: Int) {
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self.radius = radius
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super.init()
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if radius <= 0 {
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return nil
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}
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@ -425,13 +425,13 @@ class Circle: Shape {
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// 根据 Swift 类型推断，myCircle 是 Optional<Circle> 类型的变量
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var myCircle = Circle(radius: 1)
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println(myCircle?.getArea()) // Optional(3)
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println(myCircle!.getArea()) // 3
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print(myCircle?.getArea()) // Optional(3)
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print(myCircle!.getArea()) // 3
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var myEmptyCircle = Circle(radius: -1)
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println(myEmptyCircle?.getArea()) // "nil"
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print(myEmptyCircle?.getArea()) // "nil"
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if let circle = myEmptyCircle {
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// 此语句不会输出，因为 myEmptyCircle 变量值为 nil
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println("circle is not nil")
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print("circle is not nil")
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}
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@ -461,7 +461,7 @@ enum BookName: String {
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case John = "John"
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case Luke = "Luke"
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}
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println("Name: \(BookName.John.rawValue)")
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print("Name: \(BookName.John.rawValue)")
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// 与特定数据类型关联的枚举
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enum Furniture {
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@ -469,7 +469,7 @@ enum Furniture {
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case Desk(height: Int)
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// 和 String, Int 关联的枚举记录
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case Chair(brand: String, height: Int)
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func description() -> String {
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switch self {
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case .Desk(let height):
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@ -481,9 +481,9 @@ enum Furniture {
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}
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var desk: Furniture = .Desk(height: 80)
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println(desk.description()) // "Desk with 80 cm"
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print(desk.description()) // "Desk with 80 cm"
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var chair = Furniture.Chair(brand: "Foo", height: 40)
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println(chair.description()) // "Chair of Foo with 40 cm"
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print(chair.description()) // "Chair of Foo with 40 cm"
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//
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@ -512,7 +512,7 @@ protocol ShapeGenerator {
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class MyShape: Rect {
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var delegate: TransformShape?
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func grow() {
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sideLength += 2
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@ -539,21 +539,21 @@ extension Square: Printable {
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}
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}
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println("Square: \(mySquare)") // Area: 16 - ID: defaultID
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print("Square: \(mySquare)") // Area: 16 - ID: defaultID
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// 也可以给系统内置类型添加功能支持
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extension Int {
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var customProperty: String {
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return "This is \(self)"
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}
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func multiplyBy(num: Int) -> Int {
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return num * self
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}
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}
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println(7.customProperty) // "This is 7"
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println(14.multiplyBy(3)) // 42
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print(7.customProperty) // "This is 7"
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print(14.multiplyBy(3)) // 42
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// 泛型: 和 Java 及 C# 的泛型类似，使用 `where` 关键字来限制类型。
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// 如果只有一个类型限制，可以省略 `where` 关键字
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@ -566,7 +566,7 @@ func findIndex<T: Equatable>(array: [T], valueToFind: T) -> Int? {
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return nil
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}
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let foundAtIndex = findIndex([1, 2, 3, 4], 3)
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println(foundAtIndex == 2) // true
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print(foundAtIndex == 2) // true
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// 自定义运算符:
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// 自定义运算符可以以下面的字符打头:
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@ -581,11 +581,10 @@ prefix func !!! (inout shape: Square) -> Square {
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}
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// 当前值
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println(mySquare.sideLength) // 4
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print(mySquare.sideLength) // 4
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// 使用自定义的 !!! 运算符来把矩形边长放大三倍
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!!!mySquare
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println(mySquare.sideLength) // 12
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print(mySquare.sideLength) // 12
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```
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