Swift筆記：Simple Value

Value
let ，常數，編譯的時候不需要有值，但只能給一次值。
var，變數

編譯器會自動判斷value的類型，例如

var myVariable = 42

編譯器會自動判斷myVariable為整數

如果要指定值的類型，要在數值名稱後面加上類型，用冒號區隔。

let explicitDouble: Double = 70

Swift不會自動轉換類型，因此要強制轉換類型，

let label = "The width is"
let width = 94
let widthLabel = label + String(width)

轉換成String還可以用\(Variable)

let apples = 3
let oranges = 5
let appleSummary = "I have \(apples) apples."
let fruitSummary = "I have \(apples + oranges) pieces of fruit."

Array和Dictionary的使用方法

var shoppingList = ["catfish", "water", "tulips", "blue paint"]
shoppingList[1] = "bottle of water"

var occupations = [
    "Malcolm": "Captain",
    "Kaylee": "Mechanic",
]
occupations["Jayne"] = "Public Relations"

Array和Dictionary的初始化方法

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