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Stripping out HTML tags from a string

 原文  2014-09-22 21:42:10  7   10    html/ ios/ swift

Question

How do I remove HTML tags from a string so that I can output clean text?

let str = string.stringByReplacingOccurrencesOfString("<[^>]+>", withString: "", options: .RegularExpressionSearch, range: nil)
print(str)

10 answers

solution1
 172 ACCPTED  2014-09-22 22:34:42

Hmm, I tried your function and it worked on a small example:

var string = "<!DOCTYPE html> <html> <body> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html>"
let str = string.stringByReplacingOccurrencesOfString("<[^>]+>", withString: "", options: .RegularExpressionSearch, range: nil)
print(str)

//output "  My First Heading My first paragraph. "

Can you give an example of a problem?

Swift 4 and 5 version: 

var string = "<!DOCTYPE html> <html> <body> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html>"
let str = string.replacingOccurrences(of: "<[^>]+>", with: "", options: .regularExpression, range: nil)

solution2
 34  2015-12-28 08:48:04

Since HTML is not a regular language (HTML is a context-free language), you cannot use Regular Expressions. See: Using regular expressions to parse HTML: why not?

I would consider using NSAttributedString instead.

let htmlString = "LCD Soundsystem was the musical project of producer <a href='http://www.last.fm/music/James+Murphy' class='bbcode_artist'>James Murphy</a>, co-founder of <a href='http://www.last.fm/tag/dance-punk' class='bbcode_tag' rel='tag'>dance-punk</a> label <a href='http://www.last.fm/label/DFA' class='bbcode_label'>DFA</a> Records. Formed in 2001 in New York City, New York, United States, the music of LCD Soundsystem can also be described as a mix of <a href='http://www.last.fm/tag/alternative%20dance' class='bbcode_tag' rel='tag'>alternative dance</a> and <a href='http://www.last.fm/tag/post%20punk' class='bbcode_tag' rel='tag'>post punk</a>, along with elements of <a href='http://www.last.fm/tag/disco' class='bbcode_tag' rel='tag'>disco</a> and other styles. <br />"    
let htmlStringData = htmlString.dataUsingEncoding(NSUTF8StringEncoding)!
let options: [String: AnyObject] = [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: NSUTF8StringEncoding]
let attributedHTMLString = try! NSAttributedString(data: htmlStringData, options: options, documentAttributes: nil)
let string = attributedHTMLString.string

Or, as Irshad Mohamed in the comments would do it:

let attributed = try NSAttributedString(data: htmlString.data(using: .unicode)!, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil)
print(attributed.string)

solution3
 22  2019-01-30 11:23:12

Mohamed solution but as a String extension in Swift 4. 

extension String {

    func stripOutHtml() -> String? {
        do {
            guard let data = self.data(using: .unicode) else {
                return nil
            }
            let attributed = try NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil)
            return attributed.string
        } catch {
            return nil
        }
    }
}

solution4
 11  2016-02-15 12:30:00

I'm using the following extension to remove specific HTML elements:

extension String {
    func deleteHTMLTag(tag:String) -> String {
        return self.stringByReplacingOccurrencesOfString("(?i)</?\(tag)\\b[^<]*>", withString: "", options: .RegularExpressionSearch, range: nil)
    }

    func deleteHTMLTags(tags:[String]) -> String {
        var mutableString = self
        for tag in tags {
            mutableString = mutableString.deleteHTMLTag(tag)
        }
        return mutableString
    }
}

This makes it possible to only remove <a> tags from a string, eg:

let string = "my html <a href="">link text</a>"
let withoutHTMLString = string.deleteHTMLTag("a") // Will be "my  html link text"

solution5
 6  2019-08-04 09:43:23

extension String{
    var htmlStripped : String{
        return self.replacingOccurrences(of: "<[^>]+>", with: "", options: .regularExpression, range: nil)
    }
}

Happy Coding

solution6
 3  2020-08-05 10:20:13

I prefer to use a regular expression than to use NSAttributedString HTML conversion, be advised that is pretty time consuming and need to be run on the main thread too. More information here: https://developer.apple.com/documentation/foundation/nsattributedstring/1524613-initwithdata

For me this made the trick, first I remove any CSS inline styling, and later all the HTML tags. Probably not solid as the NSAttributedString option, but way faster for my case.

extension String {
    func withoutHtmlTags() -> String {
        let str = self.replacingOccurrences(of: "<style>[^>]+</style>", with: "", options: .regularExpression, range: nil)
        return str.replacingOccurrences(of: "<[^>]+>", with: "", options: .regularExpression, range: nil)
    }
}

solution7
 3  2021-05-04 11:21:43

Swift 5

extension String {
    public func trimHTMLTags() -> String? {
        guard let htmlStringData = self.data(using: String.Encoding.utf8) else {
            return nil
        }
    
        let options: [NSAttributedString.DocumentReadingOptionKey : Any] = [
            .documentType: NSAttributedString.DocumentType.html,
            .characterEncoding: String.Encoding.utf8.rawValue
        ]
    
        let attributedString = try? NSAttributedString(data: htmlStringData, options: options, documentAttributes: nil)
        return attributedString?.string
    }
}

Use:

let  str = "my html <a href='https://www.google.com'>link text</a>"

print(str.trimHTMLTags() ?? "--") //"my html link text"

solution8
 2  2018-05-13 23:09:43

swift 4 :

extension String {
    func deleteHTMLTag(tag:String) -> String {
        return self.replacingOccurrences(of: "(?i)</?\(tag)\\b[^<]*>", with: "", options: .regularExpression, range: nil)
    }

    func deleteHTMLTags(tags:[String]) -> String {
        var mutableString = self
        for tag in tags {
            mutableString = mutableString.deleteHTMLTag(tag: tag)
        }
        return mutableString
    }
}

solution9
 2  2019-05-31 09:48:58

Updated for Swift 4:

guard let htmlStringData = htmlString.data(using: .unicode) else { fatalError() }

let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
                .documentType: NSAttributedString.DocumentType.html
                .characterEncoding: String.Encoding.unicode.rawValue
             ]

let attributedHTMLString = try! NSAttributedString(data: htmlStringData, options: options, documentAttributes: nil)
let string = attributedHTMLString.string

solution10
 0  2022-07-11 17:09:07

Was able to achieve mild success using XML Tree-Based Processing and XMLDocument API (part of Foundation, so available on iOS, macOS and watchOS by default).

Made this extension. You might have to tweak it a bit according to your needs, for example:

  • The html tags found are joined by a \n , adding a new line between different <p>...</p> for example, as this worked for my own case, your case might be different. If you don't need a new line between elements, replace \n for an empty string on .joined(separator:) .

Extension

extension String {
    var removingHTML: Self? {
        let wrapped = "<xml>" + self + "</xml>"
        guard let xml = try? XMLDocument(data: .init(wrapped.utf8), options: .documentTidyXML) else { return nil }
        var children = xml.rootDocument?.children?.first?.children
        while children?.first?.name?.lowercased() == "html"
                || children?.first?.name?.lowercased() == "body" {
            children = children?
                .first {
                    $0.children?.isEmpty == false
                }?
                .children
        }
        return children
            .flatMap {
                $0.compactMap(\.stringValue)
            }?
            .joined(separator: "\n")
    }
}

Results

Using some of the examples already given on this posts

let string = "<!DOCTYPE html> <html> <body> <h1>My First Heading</h1> <p>My first paragraph.</p> </body> </html>"
print(string.removingHTML) // "My First Heading\nMy first paragraph."

let string = "LCD Soundsystem was the musical project of producer <a href='http://www.last.fm/music/James+Murphy' class='bbcode_artist'>James Murphy</a>, co-founder of <a href='http://www.last.fm/tag/dance-punk' class='bbcode_tag' rel='tag'>dance-punk</a> label <a href='http://www.last.fm/label/DFA' class='bbcode_label'>DFA</a> Records. Formed in 2001 in New York City, New York, United States, the music of LCD Soundsystem can also be described as a mix of <a href='http://www.last.fm/tag/alternative%20dance' class='bbcode_tag' rel='tag'>alternative dance</a> and <a href='http://www.last.fm/tag/post%20punk' class='bbcode_tag' rel='tag'>post punk</a>, along with elements of <a href='http://www.last.fm/tag/disco' class='bbcode_tag' rel='tag'>disco</a> and other styles. <br />"
print(string.removingHTML) // LCD Soundsystem was the musical project of producer \nJames Murphy\n, co-founder of \ndance-punk\nlabel \nDFA\nRecords. Formed in 2001 in New York City, New York, United States, the music of LCD Soundsystem can also be described as a mix of \nalternative dance\nand \npost punk\n, along with elements of \ndisco\nand other styles. \n

let string = "my html <a href=\"\">link text</a>"
print(string.removingHTML) // my html \nlink text

Check how the last example might need adjusting the extension and replacing the new line for something else, according to your needs.

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