Underline part of a string using NSMutableAttributedString in iOS 8 is not working

Question

I try to underline part of a string, for example, a \'string\' part in \'test string\' string. I\'m using NSMutableAttributedString and my sol

Answer 1

Swift 5 version of @Joss's answer with few modifications, by adding a returned NSMutableAttributedString, because I couldn't use the original solution without it.

extension NSMutableAttributedString {

func underline(term: String) -> NSMutableAttributedString {
    guard let underlineRange = string.range(of: term) else {
        return NSMutableAttributedString()
    }
    let startPosition = string.distance(from: term.startIndex, to: underlineRange.lowerBound)
    let nsrange = NSRange(location: startPosition, length: term.count)
    addAttribute(
        .underlineStyle,
        value: NSUnderlineStyle.single.rawValue,
        range: nsrange)
    return self
    }   
}

Usage:

 let myUnderLinedText = "Hello World"
 let underLinedMutableString =  NSMutableAttributedString(string: myUnderLinedText, attributes: titleAttributes).underline(term: myUnderLinedText)