Add underline on UIButton using Attributed String--- IOS

    NSMutableAttributedString *commentString = [[NSMutableAttributedString alloc] initWithString:@"Terms & Conditions"];

    

    [commentString addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:NSMakeRange(0, [commentString length])];

    

    [_m_btnTnC setAttributedTitle:commentString forState:UIControlStateNormal];