Encode String to HTML String Swift 3

Question

How can I encode a string in swift to remove all special characters and replace it with its matching html number.

Lets say I have the following String:

var mystring = "This is my String & That's it."

and then replace the special characters with its html number

& = &#38;
' = &#39;
> = &#62;

But I want to do this for all Special Characters not just the ones listed in the string above. How would this be done?

Theme · Accepted Answer · 2018-06-10 20:09:20Z

6

extension String {
    func makeHTMLfriendly() -> String {
        var finalString = ""
        for char in self {
            for scalar in String(char).unicodeScalars {
                finalString.append("&#\(scalar.value)")
            }
        }
        return finalString
    }
}

Usage:

newString = oldString.makeHTMLfriendly()

This appears to work in general (although I don't know for sure that unicode scalars always match HTML numbers).

Note that it converts everything, even things like alphanumeric characters that don't really need to be converted. It probably wouldn't be too difficult to edit it to not convert some things.

answered Jun 10, 2018 at 20:09

Theme

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Scinfu · Accepted Answer · 2017-02-17 09:01:16Z

3

Try SwiftSoup

func testEscape()throws {
    let text = "Hello &<> Å å π 新 there ¾ © »"

    let escapedAscii = Entities.escape(text, OutputSettings().encoder(String.Encoding.ascii).escapeMode(Entities.EscapeMode.base))
    let escapedAsciiFull = Entities.escape(text, OutputSettings().charset(String.Encoding.ascii).escapeMode(Entities.EscapeMode.extended))
    let escapedAsciiXhtml = Entities.escape(text, OutputSettings().charset(String.Encoding.ascii).escapeMode(Entities.EscapeMode.xhtml))
    let escapedUtfFull = Entities.escape(text, OutputSettings().charset(String.Encoding.utf8).escapeMode(Entities.EscapeMode.extended))
    let escapedUtfMin = Entities.escape(text, OutputSettings().charset(String.Encoding.utf8).escapeMode(Entities.EscapeMode.xhtml))

    XCTAssertEqual("Hello &amp;&lt;&gt; &Aring; &aring; &#x3c0; &#x65b0; there &frac34; &copy; &raquo;", escapedAscii)
    XCTAssertEqual("Hello &amp;&lt;&gt; &angst; &aring; &pi; &#x65b0; there &frac34; &copy; &raquo;", escapedAsciiFull)
    XCTAssertEqual("Hello &amp;&lt;&gt; &#xc5; &#xe5; &#x3c0; &#x65b0; there &#xbe; &#xa9; &#xbb;", escapedAsciiXhtml)
    XCTAssertEqual("Hello &amp;&lt;&gt; Å å π 新 there ¾ © »", escapedUtfFull)
    XCTAssertEqual("Hello &amp;&lt;&gt; Å å π 新 there ¾ © »", escapedUtfMin)
    // odd that it's defined as aring in base but angst in full

    // round trip
    XCTAssertEqual(text, try Entities.unescape(escapedAscii))
    XCTAssertEqual(text, try Entities.unescape(escapedAsciiFull))
    XCTAssertEqual(text, try Entities.unescape(escapedAsciiXhtml))
    XCTAssertEqual(text, try Entities.unescape(escapedUtfFull))
    XCTAssertEqual(text, try Entities.unescape(escapedUtfMin))
}

answered Feb 17, 2017 at 9:01

Scinfu

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3 Comments

aehlke Over a year ago

I'm a long-time SwiftSoup user, I need to set the text of an element without allowing it to insert HTML, so I went to the docs to look for this kind of behavior, and thought it didn't exist in SwiftSoup. So then I googled around and found this answer :)

Scinfu Over a year ago

@aehlke If you need help send me a mail

aehlke Over a year ago

I'm good now but would suggest adding this to your docs! Thank you for the wonderful library that's core to my app

P. A. Monsaille · Accepted Answer · 2022-07-18 13:58:18Z

For a little more variety:

extension String {
    var htmlCompatibleDecimalEncoded: String {
        self.unicodeScalars.reduce(into: "") { partialResult, scalar in
            partialResult.append(
                scalar.properties.isPatternSyntax ? "&#\(scalar.value)" : .init(scalar)
            )
            // For percent encoded hex-replacements we could use this:
            // "%\(String(scalar.value, radix: 16, uppercase: true))"
            // But there is a more convenient method for that.
        }
    }
    
    func htmlCompatiblePercentEncoded(allowing allowedCharacters: CharacterSet = []) -> String {
        self.addingPercentEncoding(withAllowedCharacters: allowedCharacters) ?? self
    }
}

let my: String = #"This is my "String" & That's it / <or is it?>"#

my.htmlCompatibleDecimalEncoded                                 // "This is my &#34String&#34 &#38 That&#39s it &#47 &#60or is it&#63&#62"
my.htmlCompatiblePercentEncoded(allowing: .urlQueryAllowed)     // "This%20is%20my%20%22String%22%20&%20That's%20it%20/%20%3Cor%20is%20it?%3E"
my.htmlCompatiblePercentEncoded()                               // "%54%68%69%73%20%69%73%20%6D%79%20%22%53%74%72%69%6E%67%22%20%26%20%54%68%61%74%27%73%20%69%74%20%2F%20%3C%6F%72%20%69%73%20%69%74%3F%3E"
let allowed: CharacterSet = .whitespaces.union(.alphanumerics)
my.htmlCompatiblePercentEncoded(allowing: allowed)              // "This is my %22String%22 %26 That%27s it %2F %3Cor is it%3F%3E"

aircraft · Accepted Answer · 2017-02-17 04:05:08Z

-1

Check the all special characters in html:

http://www.ascii.cl/htmlcodes.htm

And you create a Util for parsing the characters:

like this:

import UIKit

class Util: NSObject {

func parseSpecialStrToHtmlStr(oriStr: String) -> String {

        var returnStr: String = oriStr


        returnStr = returnStr.replacingOccurrences(of: "&", with: "&#38")
        returnStr = returnStr.replacingOccurrences(of: "'", with: "&#39")
        returnStr = returnStr.replacingOccurrences(of: ">", with: "&#62")
        ...


        return returnStr
    }
}

Do it yourself, create yourself's functional device.

Edit

If you think its a huge work, you check this: https://github.com/adela-chang/StringExtensionHTML

edited Feb 17, 2017 at 4:05

answered Feb 17, 2017 at 3:59

aircraft

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1 Comment

user2423476 Over a year ago

This is what I was originally doing, seemed like there had to be a simpler way to accomplish this

Mo Zaatar · Accepted Answer · 2018-03-13 00:17:30Z

-1

This is the easiest way:

let encodedValue = yourValue.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)

answered Mar 13, 2018 at 0:17

Mo Zaatar

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