Underlining text in UIButton

Question

To use interface builder to underline, one has to:

• Change it to attributed
• Highlight the text in the Attributes inspector
• Right click, choose Font and then Underline

Video someone else made https://www.youtube.com/watch?v=5-ZnV3jQd9I

From iOS6 it is now possible to use an NSAttributedString to perform underlining (and anything else attributed strings support) in a much more flexible way:

NSMutableAttributedString *commentString = [[NSMutableAttributedString alloc] initWithString:@"The Quick Brown Fox"];

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

[button setAttributedTitle:commentString forState:UIControlStateNormal];

Note: added this as another answer - as its a totally different solution to my previous one.

Edit: oddly (in iOS8 at least) you have to underline the first character otherwise it doesn't work!

so as a workaround, set the first char underlined with clear colour!

    // underline Terms and condidtions
    NSMutableAttributedString* tncString = [[NSMutableAttributedString alloc] initWithString:@"View Terms and Conditions"];

    // workaround for bug in UIButton - first char needs to be underlined for some reason!
    [tncString addAttribute:NSUnderlineStyleAttributeName
                      value:@(NSUnderlineStyleSingle)
                      range:(NSRange){0,1}];
    [tncString addAttribute:NSUnderlineColorAttributeName value:[UIColor clearColor] range:NSMakeRange(0, 1)];


    [tncString addAttribute:NSUnderlineStyleAttributeName
                      value:@(NSUnderlineStyleSingle)
                      range:(NSRange){5,[tncString length] - 5}];

    [tncBtn setAttributedTitle:tncString forState:UIControlStateNormal];

UIUnderlinedButton.h

@interface UIUnderlinedButton : UIButton {

}


+ (UIUnderlinedButton*) underlinedButton;
@end

UIUnderlinedButton.m

@implementation UIUnderlinedButton

+ (UIUnderlinedButton*) underlinedButton {
    UIUnderlinedButton* button = [[UIUnderlinedButton alloc] init];
    return [button autorelease];
}

- (void) drawRect:(CGRect)rect {
    CGRect textRect = self.titleLabel.frame;

    // need to put the line at top of descenders (negative value)
    CGFloat descender = self.titleLabel.font.descender;

    CGContextRef contextRef = UIGraphicsGetCurrentContext();

    // set to same colour as text
    CGContextSetStrokeColorWithColor(contextRef, self.titleLabel.textColor.CGColor);

    CGContextMoveToPoint(contextRef, textRect.origin.x, textRect.origin.y + textRect.size.height + descender);

    CGContextAddLineToPoint(contextRef, textRect.origin.x + textRect.size.width, textRect.origin.y + textRect.size.height + descender);

    CGContextClosePath(contextRef);

    CGContextDrawPath(contextRef, kCGPathStroke);
}


@end

You can do it in the interface builder itself.

1. Select the attribute inspector
2. Change the title type from plain to attributed

3. Set appropriate font size and text alignment

4. Then select the title text and set the font as underlined