Change UILabel attributed String color multiple times

Question

I am new to Swift 5 and am doing my first project.

I want to change the color of some texts inside my label, this is what my label looks like:

"You need to pay attention to blue texts, and even more to red texts. Try again so there is no more blue / red texts"

I want to change all the "blue" to blue, and all the "red" to red. Did some research and this is what I found:

extension NSMutableAttributedString {

    func setColor(color: UIColor, forText stringValue: String) {
       let range: NSRange = self.mutableString.range(of: stringValue, options: .caseInsensitive)
        self.addAttribute(NSAttributedString.Key.foregroundColor, value: color, range: range)
    }

}

let mainString = popUpLabel.text!
let blueString = "màu xanh" //(which is blue)
let redString = "màu đỏ" //(whish is red)
let attributedString = NSMutableAttributedString.init(string: mainString)
attributedString.setColor(color: UIColor(red: 0.24, green: 0.65, blue: 0.96, alpha: 1.00), forText: blueString)
attributedString.setColor(color: UIColor(red: 0.99, green: 0.20, blue: 0.20, alpha: 1.00), forText: redString)
popUpLabel.attributedText = attributedString

And also tried this:

let mainString = popUpLabel.text!
let blueString = "màu xanh" //(which is blue)
let redString = "màu đỏ" //(which is red)
let attributedString = NSMutableAttributedString.init(string: mainString)
let blueRange = (mainString as NSString).range(of: blueString)
let redRange = (mainString as NSString).range(of: redString)
attributedString.addAttributes([NSAttributedString.Key.foregroundColor : UIColor(red: 0.24, green: 0.65, blue: 0.96, alpha: 1.00)], range: blueRange)
attributedString.addAttributes([NSAttributedString.Key.foregroundColor : UIColor(red: 0.99, green: 0.20, blue: 0.20, alpha: 1.00)], range: redRange)
popUpLabel.attributedText = attributedString

Both works pretty well for the first blue and red, but the second blue and red stayed in black and I don't know why.

Answer 1

range(of: finds only the first occurrence of the search string.

A possible solution is Regular Expression, the pattern searches for both red and blue and changes the color accordingly.

let string = "You need to pay attention to blue texts, and even more to red texts. Try again so there is no more blue / red texts"

let pattern = "(red|blue)"

var attributedString = NSMutableAttributedString(string: string)
let regex = try! NSRegularExpression(pattern: pattern)
let matches = regex.matches(in: string, range: NSRange(string.startIndex..., in: string))
for match in matches {
    let range = Range(match.range, in: string)!
    let color : UIColor
    if string[range] == "red" {
        color = UIColor(red: 0.99, green: 0.20, blue: 0.20, alpha: 1.00)
    } else {
        color = UIColor(red: 0.24, green: 0.65, blue: 0.96, alpha: 1.00)
    }
    attributedString.addAttribute(.foregroundColor, value: color, range: match.range)
}

Answer 2

You also may use html-text converted to attributed string. Look at this answer.

Example from the answer:

let htmlText = "<medium><b><font color='#2f3744'>IPL Tamil Web Series Episode #3 | யாருடா Swetha ? | Tamil Comedy Web Series | Being Thamizhan</font></b></medium> has been succesfully scheduled on <medium><b><font color='#2f3744'>2018-05-23 08:51 PM</font></b></medium>"
    let encodedData = htmlText.data(using: String.Encoding.utf8)!
    var attributedString: NSAttributedString

    do {
        attributedString = try NSAttributedString(data: encodedData,
                                                  options:
       [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
        NSAttributedString.DocumentReadingOptionKey.characterEncoding: NSNumber(value: String.Encoding.utf8.rawValue)],
     documentAttributes: nil)
    } catch let error as NSError {
        print(error.localizedDescription)
    } catch {
        print("error")
    }