Swift 2 学习笔记 4.字符串

课程来自慕课网liuyubobobo老师

字符串

• 字符串基础

let str = "Hello,playground"
str.isEmpty  // false
let mark = "!!!"
str + mark  // Hello,playground!!!
str  // Hello,playground

• Character 和 Unicode

var str = "Hello,playground"
for char in str {  // -->Swift3
    print(char)  // 打印字符串中每一个字符
}
str + String(mark)  // Hello,playground!
str  // Hello,playground
str.append(mark)  // Hello,playground!
str  // Hello,playground!

let englishLetter: Character = "a"
let chineseLetter: Character = "中"
let dog: Character = "🐶"
let coolGuy: Character = "\u{1F60E}"

let coolLetters = "abc"
coolLetters.count  // 3 -->Swift3
let chineseLetters = "慕课网"
chineseLetters.count  //3

let cafe = "café"
let cafe2 = "cafe\u{0301}"
cafe.count  // 4
cafe2.count  // 4
cafe == cafe2  // true

• String.Index 和 Range -->Swift3

var str = "Hello, Swift"
let startIndex = str.startIndex
str[startIndex]  // "H"
let spaceIndex = str.index(startIndex, offsetBy: 6)  // " "
str[spaceIndex]
str[str.index(before: spaceIndex)]  // ","
str[str.index(after: spaceIndex)]  // "S"

let endIndex = str.endIndex  
str[startIndex..<endIndex]  // "Hello, Swift"

let range = startIndex..<spaceIndex
str[range]  // "Hello,"
str.replaceSubrange(range, with: "Hi ")  // "Hi Swift"
str.append(contentsOf: "!!!")  // "Hi  Swift!!!"
str.insert("?", at: str.endIndex)  // Hi  Swift!!!?

• String 和 NSString --> Swift4

let str = "Hello, swift"
str.uppercased()  // "HELLO, SWIFT"
str.lowercased()  // "hello, swift"
str.capitalized  // "Hello, Swift"
str.contains("swift")  // true
str.hasPrefix("Hello")  // true
str.hasSuffix("t")  // true

let str1: String = String(format: "one third is %.2f", 1.0/3.0)
let str2: String = NSString(format: "one third is %.2f", 1.0/3.0) as String
let str3: NSString = "one third is 0.33"
let newStr: Substring = str1[str1.index(str1.startIndex, offsetBy: 4)...]  // "third is 0.33" 返回一个 Substring
let newStr2: String = String(str1[str1.startIndex..<str1.index(str1.startIndex, offsetBy: 3)])  // "one" 转成String
str3.substring(from: 4)  // "third is 0.33"
str3.substring(to: 3)  // "one"
str3.substring(with: NSMakeRange(4, 5))  // "third"

let str4 = "😀😀😀"
let str5: NSString = "😀😀😀"
str4.count  // 3
str5.length  // 6

let str6 = "   ---Hi---   "
let str7: NSString = "   ---Hi---   "
str6.trimmingCharacters(in: CharacterSet(charactersIn: " -"))  // "Hi"
str7.trimmingCharacters(in: CharacterSet(charactersIn: " -"))  // "Hi"