Add color to a certain part of a string (or NSString)

addColorString.swift

 func configureTextr() -> NSAttributedString{
        let text = "first string"
        let aviso = "second string"
        
        let mainText = text! + " " + aviso!
        let attributeText = aviso
        let range = (mainText as NSString).range(of: attributeText!)
        let attributedString = NSMutableAttributedString(string:mainText)
        attributedString.addAttribute(NSForegroundColorAttributeName, value: UIColor.rentaliaLightBlue(withAlpha: 1), range: range)
        return attributedString
    }