之前我写过一篇文章介绍如何使用正则表达式来验证用户名、邮箱、URL 等格式是否正确（点击查看）。除了验证数据外，我们还可以使用正则表达式进行文字替换、或者提取工作。下面通过样例进行演示。
一、封装一个正则工具类（Regex.swift）
由于 NSRegularExpression 使用起来十分繁琐，为方便使用，我们首先对它进行封装。增加一些常用的正则处理方法。
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import Foundation/// 基于NSRegularExpression api 的正则处理工具类public struct Regex { private let regularExpression: NSRegularExpression //使用正则表达式进行初始化 public init(_ pattern: String, options: Options = []) throws { regularExpression = try NSRegularExpression( pattern: pattern, options: options.toNSRegularExpressionOptions ) } //正则匹配验证（true表示匹配成功） public func matches(_ string: String) -> Bool { return firstMatch(in: string) != nil } //获取第一个匹配结果 public func firstMatch(in string: String) -> Match? { let firstMatch = regularExpression .firstMatch(in: string, options: [], range: NSRange(location: 0, length: string.utf16.count)) .map { Match(result: $0, in: string) } return firstMatch } //获取所有的匹配结果 public func matches(in string: String) -> [Match] { let matches = regularExpression .matches(in: string, options: [], range: NSRange(location: 0, length: string.utf16.count)) .map { Match(result: $0, in: string) } return matches } //正则替换 public func replacingMatches(in input: String, with template: String, count: Int? = nil) -> String { var output = input let matches = self.matches(in: input) let rangedMatches = Array(matches[0..<min(matches.count, count ?? .max)]) for match in rangedMatches.reversed() { let replacement = match.string(applyingTemplate: template) output.replaceSubrange(match.range, with: replacement) } return output }}//正则匹配可选项extension Regex { /// Options 定义了正则表达式匹配时的行为 public struct Options: OptionSet { //忽略字母 public static let ignoreCase = Options(rawValue: 1) //忽略元字符 public static let ignoreMetacharacters = Options(rawValue: 1 << 1) //默认情况下,“^”匹配字符串的开始和结束的“$”匹配字符串,无视任何换行。 //使用这个配置，“^”将匹配的每一行的开始,和“$”将匹配的每一行的结束。 public static let anchorsMatchLines = Options(rawValue: 1 << 2) ///默认情况下,"."匹配除换行符(\n)之外的所有字符。使用这个配置，选项将允许“.”匹配换行符 public static let dotMatchesLineSeparators = Options(rawValue: 1 << 3) //OptionSet的 raw value public let rawValue: Int //将Regex.Options 转换成对应的 NSRegularExpression.Options var toNSRegularExpressionOptions: NSRegularExpression.Options { var options = NSRegularExpression.Options() if contains(.ignoreCase) { options.insert(.caseInsensitive) } if contains(.ignoreMetacharacters) { options.insert(.ignoreMetacharacters) } if contains(.anchorsMatchLines) { options.insert(.anchorsMatchLines) } if contains(.dotMatchesLineSeparators) { options.insert(.dotMatchesLineSeparators) } return options } //OptionSet 初始化 public init(rawValue: Int) { self.rawValue = rawValue } }}//正则匹配结果extension Regex { // Match 封装有单个匹配结果 public class Match: CustomStringConvertible { //匹配的字符串 public lazy var string: String = { return String(describing: self.baseString[self.range]) }() //匹配的字符范围 public lazy var range: Range<String.Index> = { return Range(self.result.range, in: self.baseString)! }() //正则表达式中每个捕获组匹配的字符串 public lazy var captures: [String?] = { let captureRanges = stride(from: 0, to: result.numberOfRanges, by: 1) .map(result.range) .dropFirst() .map { [unowned self] in Range($0, in: self.baseString) } return captureRanges.map { [unowned self] captureRange in if let captureRange = captureRange { return String(describing: self.baseString[captureRange]) } return nil } }() private let result: NSTextCheckingResult private let baseString: String //初始化 internal init(result: NSTextCheckingResult, in string: String) { precondition( result.regularExpression != nil, "NSTextCheckingResult必需使用正则表达式" ) self.result = result self.baseString = string } //返回一个新字符串，根据“模板”替换匹配的字符串。 public func string(applyingTemplate template: String) -> String { let replacement = result.regularExpression!.replacementString( for: result, in: baseString, offset: 0, template: template ) return replacement } //藐视信息 public var description: String { return "Match<\"\(string)\">" } }} |
二、使用样例
1，验证字符串格式
下面样例验证一个邮箱地址的格式是否正确。
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//初始化正则工具类let pattern = "^([a-z0-9_\\.-]+)@([\\da-z\\.-]+)\\.([a-z\\.]{2,6})$"let regex = try! Regex(pattern)//验证邮箱地址let mailAddress = "admin@hangge.com"if regex.matches(mailAddress) { print("邮箱地址格式正确")}else{ print("邮箱地址格式有误")} |
2，提取字符串
（1）获取第一个匹配结果
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//初始化正则工具类let pattern = "([\\u4e00-\\u9fa5]+):([\\d]+)"let regex = try! Regex(pattern)//原始字符串let str = "王大锤:123456,李子明:23457,李洛克:110"//获取第一个匹配对象if let first = regex.firstMatch(in: str) { print("--- 第一个匹配结果 ---") print(first) print("匹配字符串：", first.string) print("捕获组：", first.captures[0]!, first.captures[1]!) print("匹配范围：", first.range)} |
（2）获取所有的匹配结果
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//初始化正则工具类let pattern = "([\\u4e00-\\u9fa5]+):([\\d]+)"let regex = try! Regex(pattern)//原始字符串let str = "王大锤:123456,李子明:23457,李洛克:110"//获取第一个匹配对象for match in regex.matches(in: str) { print("\n--- 匹配结果 ---") print(match) print("匹配字符串：", match.string) print("捕获组：", match.captures[0]!, match.captures[1]!) print("匹配范围：", match.range)} |
3，字符串替换
（1）简单的替换
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//初始化正则工具类let pattern = "([\\u4e00-\\u9fa5]+):([\\d]+)"let regex = try! Regex(pattern)//原始字符串let str = "王大锤:123456,李子明:23457,李洛克:110"//只替换第1个匹配项let out1 = regex.replacingMatches(in: str, with: "***", count: 1)//替换所有匹配项let out2 = regex.replacingMatches(in: str, with: "***") //输出结果print("原始的字符串：", str)print("替换第1个匹配项：", out1)print("替换所有匹配项：", out2) |
（2）捕获组替换
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//初始化正则工具类let pattern = "([\\u4e00-\\u9fa5]+):([\\d]+)"let regex = try! Regex(pattern)//原始字符串let str = "王大锤:123456,李子明:23457,李洛克:110"//只替换第1个匹配项let out1 = regex.replacingMatches(in: str, with: "$1的电话是$2", count: 1)//替换所有匹配项let out2 = regex.replacingMatches(in: str, with: "$1的电话是$2") //输出结果print("原始的字符串：", str)print("替换第1个匹配项：", out1)print("替换所有匹配项：", out2) |