Swift语法基础：1

由于现在Swift的语法更新的有些快，并且官方文档的例子和Xcode 6.1.1出来的结果不一样，所以我想着要把我学习Swift语言时的一些细节分享出来～～

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1.简单值Let和Var

let: 用来定义常量
var: 用来定义变量

var a = 2
a = 1
let b = 1
// 打印出来的结果:1,1

ps：常量和变量赋值必须要和它们的类型一致。

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2.给变量或者常量设置特定的类型

let a = 2
let b = 3
let c:Double = 70
// 打印出来的结果:2,3,70.0

这样子c的类型就是Double类型了

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3.隐式声明和显式声明:

// 显示声明

let label = "The width is"
let width = 94
let widthLabel = label + String(width)
// 打印出来的结果:The width is94

//隐式声明

let apples = 3
let oranges = 5
let appleSummary = "I have (apples) apples."
let fruitSummary = "I have (apples + oranges) pieces of fruit."
// 打印出来的结果:I have 3 apples. I have 8 pieces of fruit.

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4.创建数组和字典

var shoppingList = ["catfish", "water", "tulips", "bluepaint"]
shoppingList [1] = "bottle of water"
println(shoppingList)
// 打印出来的结果: [catfish, bottle of water, tulips, bluepaint]

var occupations = [
    "Malcolm": "Captain",
    "Kaylee": "Mechanic",
]
occupations["Jayne"] = "Pu blic Relat ions"

println(occupations)
// 打印出来的结果: [Kaylee: Mechanic, Jayne: Pu blic Relat ions, Malcolm: Captain]

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5.创建一个空的数组或者字典

let emptyArray = [String]()
let emptyDictionary = Dictionary<String, Float>()

也可以用上面的例子直接生成一个空的数组

shoppingList = []
// 打印出来的结果: []

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好了, 这次我们就讲到这里, 下次我们继续~