Swift语法特色（一）

0、swift语法在语句结束时可以不用分号结束

1、swift中打印log语法不再用NSLog，还原为print

print("Hello, world!")

2、属性声明，swift用let来声明常量，var来声明变量。因为swift编译器在编译时可以推断变量/常量的类型，所以你不用明确的声明其类型。

var myVariable = 42
myVariable = 50
let myConstant = 42

如果初始值不能代表所需要的类型，需要在后面声明类型，用冒号分割。

let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70

3、如果要把类型转换为其他类型，需要显示转换

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

4、把值转换成字符串的形式也可以用()的形式，()内放变量

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

5、需要写多行的字符串内容时，可以使用三个引号（"""）来包含。

let quotation = """
I said "I have (apples) apples."
And then I said "I have (apples + oranges) pieces of fruit."
"""

6、数组和字典都可以使用方括号 [] 来进行创建，字典的最后一个元素后面可以有一个逗号。素组使用下标访问元素，字典使用key值访问元素

// 数组
var shoppingList = ["catfish", "water", "tulips", "blue paint"]
shoppingList[1] = "bottle of water"
// 字典
var occupations = [    "Malcolm": "Captain",    "Kaylee": "Mechanic",]
occupations["Jayne"] = "Public Relations"