Color all occurrences of string in swift

Question

This code

var textSearch=\"hi\"
var textToShow=\"hi hihi hi\" 
var rangeToColor = (textToShow as NSString).rangeOfString(textSearch)
var attributedString =          


        

Answer 1

Using NSRegularExpression saves you from doing all the range calculations on by yourself. This example also will highlight two words instead of just one.

let text = "If you don't have a plan, you become part of somebody else's plan."
let toHighlight = ["plan", "you"]
let range = text.nsRange(from: text.startIndex ..< text.endIndex) // full text

let rangesToHighlight: [[NSRange]] = toHighlight.map { search in
    do {
        let regex = try NSRegularExpression(pattern: search, options: [])
        let matches: [NSTextCheckingResult] = regex.matches(in: text, options: [], range: range)
        return matches.map { $0.range } // get range from NSTextCheckingResult
    } catch {
        return [NSRange]()
    }
}

let yellow = UIColor.yellow
let attributedText = NSMutableAttributedString(string: text)

let flattenedRanges: [NSRange] = rangesToHighlight.joined()
flattenedRanges.forEach { // apply color to all ranges
    attributedText.addAttribute(NSForegroundColorAttributeName,
                                value: yellow,
                                range: $0)
}