Changing Background color on NSAttributedString

I think you want NSBackgroundColorAttributeName. Such as:

[mutableAttributedString addAttribute:NSBackgroundColorAttributeName value:[UIColor yellowColor] range:selectedRange];

For Swift:

attributedString.addAttribute(NSBackgroundColorAttributeName, value: yourColor, range: NSMakeRange(0, tillLocation))

Helpful link - Different way to attribute a string