Highlighting a substring in a UILabel

Question

I can;t highlight a substring.Here is what I done(is an "duplicate" question):

Here is where I need to cast it to NSRange

for user in tweet.userMentions
{          
    let userName = user.keyword
    if let startIndex = tweetTextLabel.text?.rangeOfString("@")?.startIndex
    {
        let range = startIndex...userName.endIndex
        var atrString = NSMutableAttributedString(string:tweetTextLabel.text!)
        atrString.addAttribute(NSForegroundColorAttributeName, value: UIColor.redColor(), range: range as? NSRange)
        tweetTextLabel.attributedText = atrString
    }
}

What can I do?? Maybe there it is another function thats for swift I'm using swift 1.1, iOS 8.1 SDK

Update Still isn't highliting the text

 for user in tweet.userMentions{

                let text = tweetTextLabel.text!
                let nsText = text as NSString
                let textRange = NSMakeRange(0, nsText.length)
                let attributedString = NSMutableAttributedString(string: nsText)

                nsText.enumerateSubstringsInRange(textRange, options: NSStringEnumerationOptions.ByWords, { (substring, substringRange, enclosingRange, stop) -> () in

                    if (substring == user.keyword) {
                        attributedString.addAttribute(NSForegroundColorAttributeName, value: UIColor.blueColor(), range: substringRange)
                        println(substring)
                    }
                })
                tweetTextLabel.attributedText = attributedString
                println(attributedString)

Another update So where I updated the code still doesn't colour the substring I'm doing a twitter app that highlights with colors hashtags, urls and user screen names

Answer 1

I don't quite understand what you're trying to do, but here's a model for you to work from:

let s = "Eat @my shorts" as NSString
var att = NSMutableAttributedString(string: s as String)
let r = s.rangeOfString("@\\w.*?\\b", options: .RegularExpressionSearch, range: NSMakeRange(0,s.length))
if r.length > 0 {
    att.addAttribute(NSForegroundColorAttributeName, value: UIColor.redColor(), range: r)
}

That gives an attributed string "Eat @my shorts" where the word "@my" is red.

Hope that provides a clue...

Answer 2

Look for this extension in swift 4:

extension UILabel {

    func highlight(searchedText: String?, color: UIColor = .red) {
        guard let txtLabel = self.text?.lowercased(), let searchedText = searchedText?.lowercased() else {
            return
        }

        let attributeTxt = NSMutableAttributedString(string: txtLabel)
        let range: NSRange = attributeTxt.mutableString.range(of: searchedText, options: .caseInsensitive)

        attributeTxt.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)

        self.attributedText = attributeTxt
    }

}

EDIT: Extension improved, he can receive arguments of String

 extension UILabel {

    func highlight(searchedText: String?..., color: UIColor = .red) {
        guard let txtLabel = self.text else { return }

        let attributeTxt = NSMutableAttributedString(string: txtLabel)

        searchedText.forEach {
            if let searchedText = $0?.lowercased() {
                let range: NSRange = attributeTxt.mutableString.range(of: searchedText, options: .caseInsensitive)

                attributeTxt.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
                attributeTxt.addAttribute(NSAttributedString.Key.font, value: UIFont.boldSystemFont(ofSize: self.font.pointSize), range: range)
            }
        }

        self.attributedText = attributeTxt
    }

}