1.常量:使用let聲明

let str = "kuangjunjie"

2.變量:使用var聲明

var str = "kuangjunjie"

3.整型

 有符號整形：Int，Int8，Int16，Int32，Int64
 無符號整形：UInt，UInt8，UInt16，UInt32，UInt64

4.浮點型

 Float：32位浮點數類型
 Double：64位浮點數類型

5.布爾型：Bool

let bool1 = true
let bool2 = false

6.字符串

// (1)判斷是否為空:isEmpty
let str = ""
if str.isEmpty {
    print("空字符串")
}

// (2)獲取字符數量: str.characters.count
let str = "kuangjunjie"
print("\(str.characters.count)個字符")

// (3)檢查字符是否有特定的前綴/后綴: 
let str = "kuangjunjie"
if str.hasPrefix("kuang") {
    print("str字符串有kuang前綴")
}
if str.hasSuffix("jie") {
    print("str字符串有jie后綴")
}
//（4）還可以用“\()”在字符串里包裹變量，常量
let age = "18"
let say = "我永遠\(age)歲"

// (5）大小寫轉換：通過字符串的uppercaseString、lowercaseString屬性來訪問一個字符串的大寫/小寫
let str = "name: Kuangjunjie"
var uppercasedStr = str.uppercased()//NAME: KUANGJUNJIE
var lowercasedStr = str.lowercased()//name: kuangjunjie

7.字符: Character

var character : Character = "@"

8.元組: ( , )

let tuple = (frist: "1",second:"2")
print(tuple.frist) // 1