title: replace specific text to the image using NSMutableAttributedString and regex
body: <p>I want to replace "[img src=(IMAGE NAME)]" text to (IMAGE NAME) image. 
  but text replaced with blank. not an image. what should i do?</p>
  
  <pre><code>    guard
          let original = self.text
          else { return }
      let pattern = "\\[img src=(\\w+)\\]"
  
      do{
          let regex = try NSRegularExpression(pattern: pattern, options: [])
          let matches = regex.matches(in: original, options : [], range : NSMakeRange(0, original.characters.count))
          let attributeString = NSMutableAttributedString(string : original)
  
          for match in matches.reversed(){
              let emoticon = attributeString.attributedSubstring(from: match.rangeAt(1)).string
  
              if let image = UIImage(named : "\(emoticon)"){
                  let attributedImage = NSTextAttachment()
                  attributedImage.image = image
                  attributedImage.bounds = CGRect(x : 0, y : 0, width : image.size.width, height : image.size.height)
                  attributeString.replaceCharacters(in: match.rangeAt(0), with: NSAttributedString(attachment: attributedImage))
              }
          }
  
          self.attributedText = attributeString
      }catch{
  
      }
  </code></pre>