变量声明
@H_502_3@//变量声明 var num = 22; var m:Int = 10; num = 15;常量的声明
@H_502_3@let count = 50; let width:Double = 12.0; //count = 13;//count为常量 不能被改变字符串声明
@H_502_3@let label = "The width is"; var label1:String = "你好";变量类型转换
swift语言中类型没有隐式转换，所有类型只能强制转换@H_502_48@ @H_502_3@let widthLabel = label + String(count); var d:Double = width + Double(count);
在字符串中打印值
@H_502_3@println(label + "\(count)"); println("this is \(count)"); println("this is \(m)");//m为Double类型 println("this is \(m + n)");//m和n都为Double类型数组声明与使用
@H_502_3@var shopping = ["water","paper","tulips"];//定义一个数组 println(shopping[0]); var emptyArry = [String]();//声明一个空的String数组 shopping = [];//如果类型可以被推断的话可以这样声明一个空数组字典的声明是使用
@H_502_3@var occupation = [ "hello" : "world","good" : "morning" ] var str = occupation["good"]; var emptyDic = [String:Float]();//声明一个空的字典 var dic = [:];//类型知道的话可以这样声明一个空字典控制语句
for语句
@H_502_3@//for控制语句 for(var i = 0; i < shopping.count; i++) { println(shopping.count); println(shopping[i]); } @H_502_3@//新型for循环 for i in 0..<3 { forstLoop += i; } 相等于 for var i=0; i<3; i++ { forstLoop += i; }switch语句
switch语句不需要加break语句，语句执行以后会自动跳出。@H_502_48@ @H_502_3@//switch let str1 = "hello"; switch str1 { case "hello": println("hello world"); case "good": println("good morning"); default://default语句必须有，不然会报错 println("error"); }
使用for in便利字典和数组
@H_502_3@let intNumbers = [ "one" : [2,3,4,5,5],"two" : [1,6,8],"three" : [6,89,3] ] var largest = 0; for(kind,numbers) in intNumbers { //number前不用加var for number in numbers { if(number > largest) { largest = number; } } } println("the largerst number is \(largest)");带有？号的变量声明
@H_502_3@var optionString:String? = "hello";//表示optionString可以为nil，可以是确定值 println(optionString == nil); var optionName:String? = "John Appleseed"; var greeting = "Hello"; if let name = optionName {//使用if let处理值缺失的情况 greeting = "Hello,\(name)";//"Hello,John Appleseed" }函数
返回一个参数
@H_502_3@//后面的String是返回值类型 func greet(name:String,day:String) -> String { return "Hello \(name),Today is \(day)"; } println(greet("ttf","friday"));返回多个参数（返回元组）
@H_502_3@//参数是一个数组，返回值为最小值，最大值，总和 func calculte(scores:[Int]) ->(min: Int,max: Int,sum: Int) { var min = scores[0]; var max = scores[0]; var sum = scores[0]; for score in scores { if score < min { min = score; }else if score > max { max = score; } sum += score; } return (min,max,sum); } let scores = [1,2,7]; calculte(scores);可变参数的函数
@H_502_3@//有不确定个参数 func sumOf(numbers: Int...) -> Int { var sum = 0; for number in numbers { sum += number; } return sum; } sumOf(1,3);函数里面可以嵌套函数
@H_502_3@//函数里面嵌套一个函数 func returnFifteen() -> Int { var y = 10; func add() { y += 5; } add(); return y; } returnFifteen();函数返回一个函数
函数是swift里面的一级成员，最大，所以他也可以返回一个函数@H_502_48@ @H_502_3@//返回值是一个函数 func makeIncrementer() -> (Int -> Int) { func addOne(number: Int) -> Int { return 1 + number; } return addOne; } var increment = makeIncrementer(); increment(2);//给这个函数传递参数
函数作为参数传递
@H_502_3@func hasAnyMatches(list: [Int],condition: Int -> Bool) -> Bool { for item in list { if condition(item) { return true; } } return false; } //要传递的函数 func lessThanTen(number: Int) -> Bool { return number < 10; } var numbers = [20,10,56]; hasAnyMatches(numbers,lessThanTen);函数是特殊的闭包？
@H_502_3@//让每一个元素都乘以3 numbers.map({ (number: Int) -> Int in let result = 3 * number; return result; })如果参数类型都已经知道，下面这种方法等价@H_502_48@ @H_502_3@//让每一个元素都乘以3，并打印 let mappedNumber = numbers.map({number in 3 * number}); println(mappedNumber); @H_502_3@//从大到小排列数组 let sortedNumbers = sorted(numbers) { $0 > $1 }; println(sortedNumbers);
类的声明与使用
声明一个类
@H_502_3@class Shape { var numberOfSide = 0; func simpleDescription() -> String { return "this is \(numberOfSide)"; } }类对象创建与使用
@H_502_3@var shape = Shape();//创建类对象 shape.numberOfSide = 2;//给类的成员变量赋值 var shapeDes = shape.simpleDescription();//调用类的成员函数类的构造方法
@H_502_3@var shape = Shape(); shape.numberOfSide = 2; var shapeDes = shape.simpleDescription(); class NameShape { var numberOfSides: Int = 0; var name: String; init(name: String) {//构造方法 self.name = name; } func simpleDescription() -> String { return "this is \(numberOfSides)"; } } var nameShape = NameShape(name:"ttf");//方法传递参数时，前面要加标记 nameShape.simpleDescription();类的继承
@H_502_3@class Square: NameShape { var sideLength: Double; init(sideLength: Double,name: String) { self.sideLength = sideLength; super.init(name: name);//不能写在前面，要保证本类中先定义的先初始化 self.numberOfSides = 4; } func area() -> Double { return self.sideLength * self.sideLength; } override func simpleDescription() -> String { return "square sides of length is \(self.sideLength)"; } } var square = Square(sideLength: 10.0,name: "ttf"); square.area(); square.simpleDescription();类方法传参的时候需要显示说明
类中的方法和一般的函数不同，类中的方法传递参数的时候需要有标记，显示说明(第一个可以省略)@H_502_48@ @H_502_3@class Counter { var count: Int = 0; func increment(amout: Int,times: Int) { count += amout * times; } } var counter = Counter(); counter.increment(2,times: 4);//必须要带标记，显示声明
枚举和结构体
枚举的声明，里面也可以有方法
@H_502_3@enum Suit { case one,two,tree } let number = Suit.one;结构体创建
结构体和类很想同，结构体是传值，类是传引用@H_502_48@
