从 Swift 中的 href 中提取链接

Question

假设我有一个这样的 html 链接：

<a href = "https://mitsui-shopping-park.com/lalaport/koshien/" target="_blank"> https://mitsui-shopping-park.com/lalaport / koshien / </a>

我要提取：

<a href = "THIS LINK" target="_blank"> NOT THIS LINK </a> 

我试过了：someString.replacingOccurrences(of: "<[^>]+>", with: "", options: .regularExpression, range: nil) 但这给了我：

<a href = "NOT THIS LINK" target="_blank"> BUT THIS LINK </a>

请帮忙。

Answer 1

不需要正则表达式，您可以使用属性字符串的link 属性。

首先，让我们使用this 扩展名：

extension String{
    func convert2Html() -> NSAttributedString {

        guard let data = data(using: .utf8) else { return NSAttributedString() }

        do {
            let htmlAttrib = NSAttributedString.DocumentType.html
            return try NSAttributedString(data: data,
                                          options: [.documentType : htmlAttrib],
                                          documentAttributes: nil)
        } catch {
            return NSAttributedString()
        }
    }
}

转换这个String:

let html = "<a href = \"https://mitsui-shopping-park.com/lalaport/koshien/\" target=\"_blank\"> https://mitsui-shopping-park.com/lalaport / koshien / </a>"

到NSAttributedString:

let attrib = html.convert2Html()

然后以这种方式提取链接：

let link = attrib.attribute(.link, at: 0, effectiveRange: nil)

if let url = link as? NSURL, let href = url.absoluteString {
    print(href)  //https://mitsui-shopping-park.com/lalaport/koshien/
}

Answer 2

这是获取href=" 和结束" 之间的值的一种可能解决方案。这仅适用于字符串中的一个 href。

let html = "<a href = \"https://mitsui-shopping-park.com/lalaport/koshien/\" target=\"_blank\"> https://mitsui-shopping-park.com/lalaport / koshien / </a>"

if let hrefRange = html.range(of: "(?:href\\s*=\\s*\")[^\"]*(?:\")", options: .regularExpression) {
    let href = html[hrefRange]
    print(href)
} else {
    print("There is no href")
}

让我们分解那个正则表达式：

首先，让我们删除 RE 中所需的额外 \ 使其成为值 Swift 字符串。这给我们留下了：

(?:href\s*=\s*")[^"]*(?:")

这包括三个主要部分：

(?:href\s*=\s*") - the href, optional space, =, optional space, and opening quote
[^"]* - the actual URL - everything that isn't a quote
(?:") - the close quote

(?: ) 语法意味着里面的东西不会是返回字符串的一部分。

Answer 3

将NSRegularExpression.matches 用于正则表达式的捕获组功能。我总是使用这种方便的扩展方法：

extension String {
    func capturedGroups(withRegex pattern: String) -> [String?] {
        var results = [String?]()

        var regex: NSRegularExpression
        do {
            regex = try NSRegularExpression(pattern: pattern, options: [])
        } catch {
            return results
        }

        let matches = regex.matches(in: self, options: [], range: NSRange(location:0, length: self.count))

        guard let match = matches.first else { return results }
        let lastRangeIndex = match.numberOfRanges - 1
        guard lastRangeIndex >= 1 else { return results }

        for i in 0...lastRangeIndex {
            let capturedGroupIndex = match.range(at: i)
            if(capturedGroupIndex.length>0)
            {
                let matchedString = (self as NSString).substring(with: capturedGroupIndex)
                results.append(matchedString)
            }
            else
            {
                results.append(nil)
            }
        }

        return results
    }
}

var html = """
<a href = "https://mitsui-shopping-park.com/lalaport/koshien/" target="_blank"> https://mitsui-shopping-park.com/lalaport / koshien / </a>
"""
print(html.capturedGroups(withRegex: "href\\s*=\\s*\"([^\"]+)\"")[1])