Underline attached text not working in iPhone 6+

I want to create a method that returns the attributed text to me.

here is the code i am using

- (NSAttributedString *)getUnderlineAttributedStringForText:(NSString *)strWholeString andTextToHaveLink:(NSString *)strLink TextColor:(UIColor *)textColor LinkColor:(UIColor *)linkColor withFont:(UIFont*)font {

NSRange stringRange = NSMakeRange(0, strWholeString.length);
NSRange linkRange = [strWholeString rangeOfString:strLink];
NSLog(@"String Link :: %@",[strWholeString substringWithRange:linkRange]);
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:strWholeString];
// Paragraph Style
NSMutableParagraphStyle *paragrapStyle = NSMutableParagraphStyle.new;
paragrapStyle.alignment = NSTextAlignmentLeft;

[attributedString addAttribute:NSParagraphStyleAttributeName value:paragrapStyle range:stringRange];
[attributedString addAttribute:NSForegroundColorAttributeName value:textColor range:stringRange];
[attributedString addAttribute:NSFontAttributeName value:font range:stringRange];
[attributedString addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger: NSUnderlineStyleSingle] range:linkRange];
[attributedString addAttribute:NSForegroundColorAttributeName value:linkColor range:linkRange];

return attributedString;
}

// This is how I call the method 
[btnTermOfUse setAttributedTitle:[self getUnderlineAttributedStringForText:@"By signing up you agree to the Terms of Use" andTextToHaveLink:@"Terms of Use" TextColor:[UIColor darkGrayColor] LinkColor:[UIColor orangeColor] withFont:[UIFont systemFontOfSize:16]] forState:UIControlStateNormal];

      

        
        
        
      

    

This code works great on all devices except 6+.

edits - in 6+ only underline does not display text color change for link text. I can see an underline on an iPhone 6 or 5S.

Does anyone have any ideas regarding this?

I know there are so many questions related to this, but they did not help me, so I am posting here.