Swift - search strings in TextView and make them bold

Question

I have an UITextField with long text inside, I need to find all the occurrences of a string inside the text and make them bold. I know I should use NSMutableAttributedString for making the text bold, but how can I search specific substring inside the text?

Answer 1

You can create a textView extension that can be called on your textView outlet:

extension UITextView {    
    func makeBold(originalText: String, boldText: String) {

        let attributedOriginalText = NSMutableAttributedString(string: originalText)
        let boldRange = attributedOriginalText.mutableString.range(of: boldText)

        attributedOriginalText.addAttribute(NSAttributedString.Key.font, value: UIFont.boldSystemFont(ofSize: 13), range: boldRange)
        self.attributedText = attributedOriginalText
    }
}

How to use:

@IBOutlet weak var textView: UITextView!

textView.makeBold(originalText: "Make bold", boldText: "bold")