摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //字典 Dictionary (键值，数据对应的无序数据集合) //声明字典 var dict:[Stri 阅读全文

摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //容器类 ////1.数组 Array // ////一般形式 //var numbers:[Int] = 阅读全文

摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //可选型 Optional var errorCode:Int = 404 var errorCode1: 阅读全文

摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //字符串 //空字符串 var emptyString = "" var emptyString2 = S 阅读全文

摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //赋值符号 //var a = 3 //控制流 （顺序结构， 循环结构， 选择结构） //循环结构 //f 阅读全文

摘要：//: Playground - noun: a place where people can play import UIKit var str = "Hello, playground" //常量 let let maxNum = 1000 //maxNum = 2000 //变量 var va 阅读全文