初识Swift

Swift语言是继OC之后的又一热门语言并且还有取而代之的架势。最近，学习了Swift的一点皮毛，随手敲下笔记。

//1.在swift中定义变量，let定义的是常量，var定义的是变量let name = "jack" //定义出一个常量它会隐式转换成String类型let name1 : String = "小明" //如果给定类型，后边赋值的时候需要根据类型进行赋值let age : Int  = 18 //如果定义常量最好给定初始值，如果定义变量可以不给定初始值var age1 : Int? //表示age1类型为可选类型，它的值可以为空var char : Character = "A"var flag : Bool = true //在定义bool时变量只有true和false

了解了Swift的变量定义，下边我们就要熟悉Swift的各种简单应用

//一.字符串//1.创建空的字符串var str_emperty = ""print(str_emperty)var str1_emperty = String()print(str1_emperty)//2.判断字符串是否为空if str_emperty.isEmpty{    print("为空")}//3.字符串拼接var str_url = "http://"var str = "www.baidu.com"let str_new_url = str_url + str_urlprint("百度网址:\(str_new_url)")//4.获取字符串的长度var str1 : String = "asd"print(str1.characters.count)//5.字符串的比较var str2 = "mlgb"var str3 = "wasd"if str2 != str3{    print("两个字符串不相等")}//二、数组//1.定义一个数组，其中的元素类型必须相同var nameArray = ["jack","tom","jim","lily"]var nameArray1 = ["jack","gg","马二丹","张二狗"]print(nameArray1)//2.定义一个空的数组let array = Array<String>()print(array)//3.访问数组的内部元素，根据下表取值print(nameArray1[2])//4.向数组中添加元素var int_array = Array<Int>()int_array.append(123)int_array.append(456)int_array.append(789)print(int_array)//5.使用运算符添加元素int_array += [12,14,26,67]print(int_array)//6.将某元素插入到具体位置int_array.insert(222, atIndex: 1)print(int_array)//7.移除某个元素int_array.removeAtIndex(0)print(int_array)//8.移除所有元素int_array.removeAll()print(int_array)//三、字典//1.定义一个字典变量var dic : Dictionary<String,Int> = ["a":18,"b":12,"c":16,"d":10]print(dic)//2.定义一个空的字典var dic1 : Dictionary<String,Int> = [:]print(dic1)var dic2 = Dictionary<String,Int>()print(dic2)//3.往字典中添加键值对dic["e"] = 23print(dic)//4.修改字典中的内容dic["e"] = 999print(dic["e"])print(dic)//5.删除字典中的内容dic.removeValueForKey("e")print(dic)//四、元组//1.定义一个元组let status = ("蓝鸥1班",["ios","Html5"])print(status)let statusNew : (String,Array) = ("蓝鸥2班",["班花","班支书"])print(statusNew)//2.取出元组中的元素//方法一：直接赋值给常量，并通过使用标记名来获取对应的值let statu : (classroom:String,zhiwei:Array) = statusNewvar classInfo = statu.classroom + statu.zhiwei[0] + statu.zhiwei[1]print(classInfo)//方法二:通过下标去获取元素let classInfos = statu.0 + statu.1[0]print(classInfos)

定义完变量之后，我们再来看看Swift的逻辑关系怎么设定

//1.无参无返回func function()->Void{    print("111")}function()//2.有参无返回func function1(name str:String)->Void{    print(str)}function1(name: "jack")//3.有返回值，无参func function2()->String{    return "222"}print(function2())//4.有返回，有参func function3(name str:String)->Int{    print("333")    return 0;}print(function3(name: "lily"))//5.函数返回值为元组类型func function5(num1 : Int,num2 : Int)->(Int,Int,Int){    return(num1 + num2,num1 - num2,num1 * num2)}print(function5(5, num2: 2))//6.外部参数和内部参数，外部参数在调用的时候回显示出来，内部参数只是在内部调用func function6(first one:Int,second two:Int){    print((one,two))}function6(first: 4, second: 6)//6.如果不想显示外部的参数:"_"的作用就是忽略func function7(one:Int,_ two:Int){    print(one,two)}function7(2, 4)//7.函数嵌套func test1(){    func test2()    {        func test3()        {            print("hello")        }        test3()        print("world")    }    test2()    print("!!")}test1()//8.inoutfunc test(inout name:String){    name = "jack"    print(name)}var myName = "MB"test(&myName)print("myName:" + myName)