Swift 获取字符串中两个字符串之间的字符串

在Swift编程语言中，有时我们需要从一个字符串中提取出两个特定字符串之间的内容。这种情况可能出现在我们需要处理用户输入的文本，或者在处理网络请求的返回结果时。幸运的是，Swift提供了一些简便的方法来实现这个目标。

swift
let str = "Hello, World! I am learning Swift."
let startString = "Hello, "
let endString = " I am"
if let range = str.range(of: startString), let endIndex = str.range(of: endString)?.lowerBound {
    let extractedString = str[range.upperBound..    print(extractedString) // 输出: World!
} else {
    print("未找到匹配的字符串")
}

swift
import Foundation
let str = "Hello, World! I am learning Swift."
let startString = "Hello, "
let endString = " I am"
let pattern = "\(startString)(.*?)(\(endString))"
if let regex = try? NSRegularExpression(pattern: pattern, options: []) {
    let matches = regex.matches(in: str, options: [], range: NSRange(location: 0, length: str.utf16.count))
    if let match = matches.first {
        let extractedString = (str as NSString).substring(with: match.range(at: 1))
        print(extractedString) // 输出: World!
    } else {
        print("未找到匹配的字符串")
    }
} else {
    print("无效的正则表达式")
}