Hashtags in Arabic language crashes the app

Question

I have a hashtags resolver UITextView extension that turns any word with \"#\" before it to a tappable blue link. It is working fine except when tapping on Arabic hashtags.<

Answer 1

What I guess could be the issue (either on tag or hash)...

You do:

attrString.addAttribute(NSAttributedStringKey.link, value: "hash://\(stringifiedWord)", range: matchRange)

But if you'd use a URL object (let url = URL.init(string:"hash://\(stringifiedWord)")) you'll see it may be nil in case of invalid string url and in your case arabic characters seem to be invalid.

The delegate method func textView(_ textView: UITextView, shouldInteractWith URL: URL, in characterRange: NSRange) -> Bool is giving a URL object in parameters, and because your method is not called when you don't have a valid url, I guess that inner line in Apple's code assume it's a valid url, doesn't check it and crashes. That would explain why your method isn't called and crash before entering yours.

Solution: Use percent escaped characters. Instead of putting value: "hash://\(stringifiedWord)", do value: "hash://\(stringifiedWord.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed))" or other character set allowed.

In the delegate method you are already removing the percent escape: let hash = path.removingPercentEncoding?.components(separatedBy: "://").last so you don't have to add anything there.

Additional note: You are doing if word.hasPrefix("#") and `if word.hasPrefix("@") almost the same thing (just the scheme change), you could simplify/factorize that, sample code not tested:

let dict = ["#":"mention://", "@": "hash://"]
for (key, value) in dict
{
   if word.hasPrefix(key)
   {
       let matchRange:NSRange = nsText.range(of: word as String)
       var stringifiedWord:String = word as String
       stringifiedWord = String(stringifiedWord.dropFirst(key.count))
       let espcapedWord  = stringifiedWord.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed
       let stringURL = "\(value)\(escapedWord)"
       if let url = URL.init(string:stringURL) //That should you avoid any crash just in case
       {
           attrString.addAttribute(.link, value: stringURL, range: matchRange)
       }
       else
       {
            print("Oooops with \(stringifiedWord) invalid URL: \(stringURL)")
       }
   }
}

Edit: Depending on the iOS version (tested on Simulator), it could make it crash, or simply not call the delegate method because of the invalid URL.