//----------------  0.1 一些简单类型的值  ---------------

1. let 是常量    var是变量    :  用于明确类型

var myVariable = 42

myVariable = 50//变量

let myConstant = 42//常量

let floatV:Float = 4//小数

2. 用 \() 来取变量或者常量值的，括号中可以用计算符号

let myStr = "\\()是用来取变量或者常量值的，括号中可以用计算符号 \(myConstant+myVariable)"

let myStr1 = "啦啦啦\(myStr)"

3.对于多行显示的字符串用"""(三个"),注意 """ 要单占一行

let apples = 3

let oranges = 5

let multilineString = """

Even though there'    s whitespace to the left,

the actual lines aren't indented.

I still have \(apples + oranges) pieces of fruit.

"""

4.数组和字典的初始化都用[]  结尾可以使用 ,

var shoppingList = ["catfish", "water", "tulips", "blue paint"] //初始化数组

shoppingList[1] = "bottle of water" //根据下标修改字符串

print(shoppingList)

var occupations = [

"Malcolm": "Captain",

"Kaylee": "Mechanic",

] //初始化字典

occupations["Jayne"] = "Public Relations"//添加键值对

print(occupations)

occupations["Kaylee"] = "Public Relations"//根据键更改对应值

print(occupations)

print(occupations["Kaylee"]!)//字典取值用[""]

5.创建空字典和空数组 [] 中应该包含成员类型  后面的()表示：调用init方法(使用initializer语法)

let nilArr = [String]()

let nilDic = [String:NSInteger]()