String, Character

String 在 Swift 中使用双引号（”）作为界限：

let greeting = "Hello!"  // greeting‘s type is String

Character 可以从string初始化，只要只包含一个字符：

let chr: Character = "H" // valid
let chr2: Character = "??" // valid
let chr3: Character = "abc" // invalid - multiple grapheme clusters

字符串插入值

String interpolation 允许注入一个表达式，可以是任何值，包括字符串，整数，浮点数和其他各种。

语法是用一个斜杠，后面紧跟着一对括号括起来的值：\(value)。任何有效的表达式都可以出现在括号里，包括函数调用。

let number = 5
let interpolatedNumber = "\(number)"  // string is "5"
let fortyTwo = "\(6 * 7)"             // string is "42"

let example = "This post has \(number) view\(number == 1 ? "" : "s")"
// It will output "This post has 5 views" for the above example.
// If the variable number had the value 1, it would output "This post has 1 view" instead.

特殊的字符

• \0
  空字符
• \
  斜杠
• \t
  tab符
• \v
  纵向tab
• \r
  回车符
• \n
  换行符
• \”
  双引号
• \’
  单引号
• \u{n}
  Unicode 符号

比如：

let message = "Then he said, \"I \u{1F496} you!\""

print(message) // Then he said, "I ?? you!"