Swift语法快速索引
在WWDC的演示中就可以看出来Swift这个更接近于脚本的语言可以用更少的代码量完成和OC同样的功能。但是对于像我一样在战争中学习战争的同学们来说，天天抱着笨Swift Programming Language Reference之类的大部头看不实际。毕竟还是要养家糊口的。而且，那么1000+页内容讲的东西不是什么都要全部在平时工作中用到的。咱们就把平时用到的全部都放在一起，忘记了立马翻开看看，不知不觉的就学会了之后变成习惯。这样多省事。 变量 1 // Variable 2 var int_variable = 1 // 类型推断 3 var message : String 4 var x = 0.0, y = 0.0, z = 0.0 常量 // Constant let const_int = 1 //const_int = 10 ERROR: can not assign to let value 字符串 // String // 1. 定义 var empty_string = "" var another_empty_string = String() // 2. 拼接 var hello_string = "hello" var world_string = " world" hello_string += world_string // hello world let multiplier = 3 //let multiplier_message = "\(mulitplier) times 2.5 is \(Double(multiplier) * 2.5)" // 3. 比较 var hello_world_string = "hello world" hello_string == hello_world_string // all are "hello world", result is true if hello_string == hello_world_string { println("These two are equal") } Tuple // Tuple // 1. Unnamed tuple let http_not_found = (404, "Not Found") println("tuple item 1 \(http_not_found.0), tuple item 2 \(http_not_found.1)") // 2. Named tuple let (statusCode, statusMessage) = (404, "Not Found") statusCode // 404 statusMessage // "Not Found" let http_not_found2 = (statusCode:404, statusMessage:"Not Found") http_not_found2.statusCode // 404 http_not_found2.statusMessage // "Not Found" // 3. return tuple func getHttpStatus() -> (statusCode : Int, statusMessage : String){ // request http return (404, "Not Found") } 数组 // Array // 1. 定义 //var empty_array = [] // 在swift里没事不要这样定义数组。这是NSArray类型的，一般是Array<T>类型的 var empty_array : [Int] var empty_array2 = [Int]() var fire_works = [String]() var colors = ["red", "yellow"] var fires : [String] = ["small fire", "big fire"]; // Xcode6 beta3里数组的类型是放在方括号里的 var red = colors[0] // 2. append & insert colors.append("black") colors += "blue" colors += fires colors.insert("no color", atIndex: 0) // 3. update colors[2] = "light blue" //colors[5...9] = ["pink", "orange", "gray", "limon"] // 4. remove colors.removeAtIndex(5) //colors[0] = nil ERROR! // other colors.isEmpty colors.count 字典 // Dictionary // 1. 定义 var airports : Dictionary<String, String> = ["TYP":"Tokyo", "DUB":"Boublin"] var airports2 = ["TYP":"Tokyo", "DUB":"Boublin"] var empty_dic = Dictionary<String, String>() var empty_dic2 = [:] // 2. update airports.updateValue("Dublin International", forKey: "DUB") airports["DUB"] = "Dublin International" // 3. insert airports["CHN"] = "China International" // 4. check exists if let airportName = airports["DUB"] { println("The name of the airport is \(airportName).") } else{ println("That airport is not in the airports dictionary.") } // 5. iterate for (airportCode, airportName) in airports{ println("\(airportCode):\(airportName)") } // 6. remove airports.removeValueForKey("TYP") airports["DUB"] = nil 枚举 // Enum // 1. defination & usage enum PowerStatus: Int{ case On = 1 case Off = 2 } enum PowerStatus2: Int{ case On = 1, Off, Unknown } var status = PowerStatus.On enum Barcode { case UPCA(Int, Int, Int) case QRCode(String) } var product_barcode = Barcode.UPCA(8, 8679_5449, 9) product_barcode = .QRCode("ABCDEFGHIJKLMN") switch product_barcode{ case .UPCA(let numberSystem, let identifier, let check): println("UPC-A with value of \(numberSystem), \(identifier), \(check)") case .QRCode(let productCode): println("QR code with value of \(productCode)") } 方法 // Function // 1. 定义 func yourFuncName(){ } // 2. 返回值 func yourFuncNameWithReturnType()->String{ return "" } // 3. 参数 func funcWithParameter(parameter1:String, parameter2:String)->String{ return parameter1 + parameter2 } funcWithParameter("1", "2") // 4. 外部参数名 func funcWithExternalParameter(externalParameter p1:String) -> String{ return p1 + " " + p1 } funcWithExternalParameter(externalParameter: "hello world") func joinString(string s1: String, toString s2: String, withJoiner joiner: String) -> String { return s1 + joiner + s2 } joinString(string: "hello", toString: "world", withJoiner: "&") // 外部内部参数同名 func containsCharacter(#string: String, #characterToFind: Character) -> Bool { for character in string { if character == characterToFind { return true } } return false } containsCharacter(string: "aardvark", characterToFind: "v") // 默认参数值 func joinStringWithDefaultValue(string s1: String, toString s2: String, withJoiner joiner: String = " ") -> String { return s1 + joiner + s2 } joinStringWithDefaultValue(string: "hello", toString: "world") //joiner的值默认为“ ” // inout参数 func swapTwoInts(inout a: Int, inout b: Int) { let temporaryA = a a = b b = temporaryA } var someInt = 3 var anotherInt = 107 swapTwoInts(&someInt, &anotherInt) println("someInt is now \(someInt), and anotherInt is now \(anotherInt)") // prints "someInt is now 107, and anotherInt is now 3 类 // Class // 1. 定义 class NamedShape { var numberOfSides: Int = 0 var name: String // *这样定义的初始化函数，其参数在调用的时候必须作为外名称使用 init(name: String) { self.name = name } // *这样定义的参数，在初始化的时候可以不使用外名称 init(_ nickName: String){ self.name = nickName } func simpleDescription() -> String { return "A shape with \(numberOfSides) sides." } }// 2. 继承 & 函数重载 & 属性getter setter 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 } // 函数重载 override func simpleDescription() -> String { return "A square with sides of length \(sideLength)." } } class EquilateralTriangle: NamedShape { var sideLength: Double = 0.0 init(sideLength: Double, name: String) { self.sideLength = sideLength super.init(name: name) numberOfSides = 3 } // 属性的getter setter 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)." } } // 3. 使用 var triangle = EquilateralTriangle(sideLength: 3.1, name: "a triangle") triangle.perimeter triangle.perimeter = 9.9 triangle.sideLength 使用闭包给属性赋初值 struct Checkerboard { let boardColors: Bool[] = { var temporaryBoard = Bool[]() var isBlack = false for i in 1...10 { for j in 1...10 { temporaryBoard.append(isBlack) isBlack = !isBlack } isBlack = !isBlack } return temporaryBoard }() func squareIsBlackAtRow(row: Int, column: Int) -> Bool { return boardColors[(row * 10) + column] } } 类（二） 1. 属性的初始化 2. init函数中修改常量属性 struct Color{ // 在初始化函数中可以修改这些在定义时没有给出初始值的属性 let red, green, blue: Double // stored property（就是下面这样定义的），如果是optional的（结尾时？活着！），可以在初始化函数 // 中不给出初始值，否则必须给出初始值。 var alpha: Double! init(r red: Double, green: Double, blue: Double){ self.red = red self.green = green self.blue = blue } init(white: Double){ red = white green = white blue = white } init(_ aColor: Double){ self.red = aColor self.green = aColor self.blue = aColor } } 3. 构造函数 // 默认init函数 class ShoppingItem { var name: String? // var quantity: Int // 编译错误，要使代码正确需要注释掉这一句 var purchased = false // 除非定义的属性全部都有初始值。optional的属性的默认值是nil。 // 否则的话必须显示定义一个init函数。 init(){ } init(name: String, purchased: Bool){ self.name = name self.purchased = purchased } // 结构体等自定义值类型可以直接在一个init函数中使用self.init(...)的方式调用 // 其他的init函数。但是在class（引用类型）中需要显示制定convenience关键字 // 才可以调用其他的init函数 convenience init(name: String){ self.init(name: "hello", purchased: true) } } var item = ShoppingItem() struct Color{ // 在初始化函数中可以修改这些在定义时没有给出初始值的属性 let red, green, blue: Double // stored property（就是下面这样定义的），如果是optional的（结尾时？活着！），可以在初始化函数 // 中不给出初始值，否则必须给出初始值。 var alpha: Double! init(r red: Double, green: Double, blue: Double){ self.red = red self.green = green self.blue = blue } //在init函数中调用其他init函数 init(white: Double){ // red = white // green = white // blue = white self.init(r: 1.0, green: 2.0, blue:1.0) } } convenience的init函数只能在本类中调用。而一般的init函数（也就是designated init）可以在继承的链中在一个类中调用super类的init函数。 继承 不想什么被继承就在什么的前面放个final关键字（以前有@号，现在木有了）。如果在class前面放final关键字的话，那么整个类不可以被继承。 class ShoppingListItem: ShoppingItem{ final var wishListed: Bool? // 不被继承 override init(){ super.init(name: "what", purchased: false) } } 析构函数 class Vehicle{ var numberOfWheels = 0 var description: String{ return "\(numberOfWheels) wheel(s)" } deinit{ // 析构具体内容 } } 析构函数执行的特点： 1. 系统自动调用，不允许手动调用 2. 执行完本类调执行super类的 3. 执行完析构函数之后实例才释放，所以可以析构函数里可以访问全部属性的值 WEAK和UNOWNED关键字 class Customer{ let name: String var card: CreditCard? init(name: String) { self.name = name } } class CreditCard{ let number: Int /* * weak和owned关键字都用来修饰属性的，为了防止循环引用造成的内存无法释放。 * 区别就在于unowned是一定要有值的。所以unowned只可以用在非可选类型上（non-optional type） */ unowned let customer: Customer init(number: Int, customer: Customer){ self.number = number self.customer = customer } } 在闭包中也会出现这样的问题。如果在闭包中使用了self.xxxProperty也会出现对类实例本身的一个强引用，从而出现了循环引用。PS：在闭包中使用类成员的时候必须要用self.的写法。 } } class HTMLElement { let name: String let text: String? lazy var asHTML: () -> String = { [unowned self] in if let text = self.text { return "<\(self.name)>\(text)</\(self.name)>" } else { return "<\(self.name) />" } } init(name: String, text: String? = nil) { self.name = name self.text = text } deinit { println("\(name) is being deinitialized") } } 其他稍后补充 欢迎加群互相学习，共同进步。QQ群：iOS: 58099570 | Android: 572064792 | Nodejs：329118122 做人要厚道，转载请注明出处！ 本文转自张昺华-sky博客园博客，原文链接：http://www.cnblogs.com/sunshine-anycall/p/3851717.html ，如需转载请自行联系原作者
