如何在swift [Archived]中从字符串中提取所选字符

let str = "Hello, World!"
if let prefix = str.prefix(5) {
    print(prefix) // 输出: "Hello"
}
if let suffix = str.suffix(6) {
    print(suffix) // 输出: "World!"
}

// 不推荐使用，仅作参考
let str = "Hello, World!"
if let substring = str.substring(from: str.index(str.startIndex, offsetBy: 7), to: str.index(str.startIndex, offsetBy: 12)) {
    print(substring) // 输出: "World"
}

let str = "Hello, World!"
if let startIndex = str.firstIndex(of: "W"),
   let endIndex = str.firstIndex(of: "!") {
    let substring = str[startIndex..<endIndex]
    print(substring) // 输出: "World"
}

let str = "apple,banana,grape"
let parts = str.split(separator: ",")
for part in parts {
    print(String(part)) // 输出: "apple", "banana", "grape"
}

import Foundation

let str = "Name: John Doe, Age: 30"
do {
    let regex = try NSRegularExpression(pattern: "Name: (\\w+ \\w+)")
    let range = NSRange(location: 0, length: str.utf16.count)
    if let match = regex.firstMatch(in: str, options: [], range: range),
       match.numberOfRanges == 2 {
        let nameRange = Range(match.range(at: 1), in: str)!
        let name = String(str[nameRange])
        print(name) // 输出: "John Doe"
    }
} catch {
    print("Invalid regex")
}

let str = "Hello, World!"
if let startIndex = str.firstIndex(of: "W"),
   let endIndex = str.firstIndex(of: "!"),
   endIndex > startIndex {
    let substring = str[startIndex..<endIndex]
    print(substring) // 输出: "World"
} else {
    print("Invalid indices")
}

let str = "Name: John Doe, Age: 30"
do {
    let regex = try NSRegularExpression(pattern: "Name: (\\w+ \\w+)")
    let range = NSRange(location: 0, length: str.utf16.count)
    if let match = regex.firstMatch(in: str, options: [], range: range),
       match.numberOfRanges == 2 {
        let nameRange = Range(match.range(at: 1), in: str)!
        let name = String(str[nameRange])
        print(name) // 输出: "John Doe"
    } else {
        print("No match found")
    }
} catch {
    print("Invalid regex")
}