Swift5.0 基本语法

import UIKit

//1.输出
print("hello, playground")

//2.常量与变量
let a =3
var b = 4

//3.指明类型
letletIntger :Int=70
letletDouble :Double=70.0
letletString:String="Hello swift"

//4.转换字符串:String() 或 \()
letmyString ="myInt is "
letmyInt =94
letmyString2 =myString+String(myInt)
letmyString3 ="myInt is \(myInt)"

//5.数组创建与调用
var array = ["one","two","three","four"]
vargetTwo =array[1]

//6.数据字典创建与调用
var dictionary = ["name":"David","age":18,"sex":"man"] as [String:Any]
let age = dictionary["age"]

//7.for语句
foriteminarray{
    print(item)
}

//8. 函数
funcgetUserName(loginName:String)->String{
    returnloginName +" and Lily"
}
getUserName(loginName:"david")

//9.枚举
enum Week{
    case 星期一
    case 星期二
    case 星期三
    case 星期四
    case 星期五
    case 星期六
    case 星期天
}

//10.Switch语句
vartoday = "星期一"
switch today {
case "星期一":
    print("今天是星期一")
default:
    print("不知道今天星期几")
}

//11.类
classPerson :NSObject{
    varuserName:String;
    varuserAge = 18;
    override init() {
        userName=""
    }
}

var david =Person()
david.userName
david.userAge