Swift 字符串

1，遍历字符串

for character in "Dog!????" {

println(character)

}

2，连接字符串和字符+(append)

3,字符串插值

字符串插值是一种全新的构建字符串的方式，可以在其中包含常量、变量、字面量和表达式。您插入的字符串字面量的每一项都被包裹在以反斜线为前缀的圆括号中：

let multiplier = 3

let message = "\(multiplier) times 2.5 is \(Double(multiplier) * 2.5)"

// message is "3 times 2.5 is 7.5"

4,比较字符串

字符串相等

如果两个字符串以同一顺序包含完全相同的字符，则认为两者字符串相等：

let quotation = "We're a lot alike, you and I."

let sameQuotation = "We're a lot alike, you and I."

if quotation == sameQuotation {

println("These two strings are considered equal")

}

前缀/后缀相等

通过调用字符串的 hasPrefix/hasSuffix 方法来检查字符串是否拥有特定前缀/后缀。两个方法均需要以字符串作为参数传入并返回 Boolean 值。两个方法均执行基本字符串和前缀/后缀字符串之间逐个字符的比较操作。

var act1SceneCount = 0

for scene in romeoAndJuliet {

if scene.hasPrefix("Act 1 ") {

++act1SceneCount

}

}

var mansionCount = 0

var cellCount = 0

for scene in romeoAndJuliet {

if scene.hasSuffix("Capulet's mansion") {

++mansionCount

} else if scene.hasSuffix("Friar Lawrence's cell") {

++cellCount

}

}

println("\(mansionCount) mansion scenes; \(cellCount) cell scenes")

大写和小写字符串

您可以通过字符串的 uppercaseString 和 lowercaseString 属性来访问一个字符串的大写/小写版本。

let normal = "Could you help me, please?"

let shouty = normal.uppercaseString

// shouty 值为 "COULD YOU HELP ME, PLEASE?"

let whispered = normal.lowercaseString

// whispered 值为 "could you help me, please?"