swift基础之<二>

//类型安全，swift中不支持隐式转换//var c = 100//var c1 = 100.85////let res = c + c1//总结：swift 中不同数据类型，不能赋值和运算//---------循环语句---------//for in /for/while/ do whilevar sum_1 = 100while(sum_1 > 50){   //-- ,++ 不能空格    sum_1--    print("sum_1 \(sum_1)")}//do while repeat{    sum_1--    print("sum_1 \(sum_1)")}while(sum_1 > 50)//总结：do while 换成了repeat while 其他语法没有改变//分支语句// if elsevar girlfriend = (name:"XXX",age:30)if girlfriend.age <= 18{    print("too young too naive")}else if girlfriend.age > 18 && girlfriend.age <= 22{    print("I want you")}else if girlfriend.age > 22 && girlfriend.age <= 30{    print("not bad")}else{    print("OMG")}//Switchlet source = 68;switch source{case 0..<60:    print("不及格")case 60..<80:    print("及格")   fallthroughcase 80..<90:    print("良好")case 90..<100:    print("优秀")case 100:    print("满分")default :    print("输入有误")}//Switch判断条件可以是字符串let let_str = "lee"switch let_str{    case "zz":    print("doubi")    case "lee":    print("cool")default:    print("yeah")}let point = (0,0)switch point{case (0,0):    print("原点")case(0,_)://占位符_    print("y轴上")case(_,0):    print("x轴上")default:    print("其他")}/*1：switch不需要加break，也就是默认没有贯穿，判断条件不用加（）2: 如果想实现贯穿需要加 fallthrough3: switch可以以字符串和元组作为判断条件*///----------函数----------//1.无参无返回值函数func method1() ->Void{}//省略版 无参无返回值函数func method2(){    print("我是无参无返回值的函数")}//2:无参有返回值func method3() ->String{   return "wp"}let func_str = method3()print(func_str)//3.有参无返回值func method4(A:Int,B:String,C:Float) ->Void{}//4.有餐有返回值func method5(A A:Int,B:Int) ->Int{    if A > B    {        return A    }else    {        return B    }    // return A > B ? A : B}let func_int1 = method5(A : 100, B : 25)print(func_int1)//5.有参有返回值（返回多个值）func method6 (name:String,age:Int,gender:String) ->(String,Int,String){    return("ez",18,"boy")}print(func_int1)let fun_str_2 = method6("s", age: 12, gender: "female")print(fun_str_2.0)//交换函数参数的值(如果改变参数函数，需要在参数前面加一个关键字：inout)func method7(inout A:Int,inout B:Int) ->Void{    let temp = A          A = B    B = temp}var A = 100var B = 999method7(&A, B: &B)print(A)//---------------------------枚举-----------------------enum Season : Int{    case Spring = 0    case Summer    case fall    case winter}//根据C语言对比，枚举多了Case关键词，不用加逗号“，” Swift中枚举为 int 类型的， 不会默认从0开始let enum_1 = Season.Spring//typealias Newname = Seasonswitch enum_1{case.Spring:    print("春天")case.Summer:    print("夏天")case.fall:    print("秋天")default:    print("冬天")}print(enum_1)//总结：Switch用枚举作为判断条件，case后面是用“.”来获取枚举的值//switch中，当所有case条件满足，default可以省略，若不满足必须加default//第二种枚举（可以用字符串定义枚举值）enum Season2:String{    case Spring = "春天"    case Summer = "夏天"    case Autumn = "秋天"    case Winter = "冬天"}//----------------结构体--------------// Swift结构体，相当于swift中的类。结构体是值类型（重新拷贝一份值，修改拷贝的值对原来的值没有影响，类是引用类型（共用一个内存地址，原值会改变影响新值）struct Person {    //对象的属性    var name: String    var age : Int    //对象的方法    func sayHello()->Void    {        print("你好")    }    //类方法 static func sayHi() ->Void    {        print("HI")    }   //类属性    static var personName:String?}//生成一个对象let per1 = Person(name: "z", age: 21)//调用对象方法per1.sayHello()//输出对象的名字print(per1.name)//调用类方法Person.sayHi()Person.personName = "lisi"var p1 = Person.init(name: "lol", age: 111)var p2 = p1print(p2.name)p1.name = "zzz"print(p2.name)print(Person.personName!)//类class Student {    var name: String?//类，声明属性必须用可选方法    var age: Int?    func sayFuck()->Void    {        print("fuck")    }    static var studentName:String?}var stu1 = Student()stu1.name = "www"stu1.age  = 35var stu2 = stu1print(stu2.name)stu1.name = "hole"print(stu2.name)