Underlining text in UIButton

Question

Can anyone suggest how to underline the title of a UIButton ? I have a UIButton of Custom type, and I want the Title to be underlined, but the Interface Builder does not provide any option to do so.

In Interface Builder when you select the Font Option for a Button, it provides option to select None, Single, Double, Color but none of these provide any changes to the Title on the Button.

Any help appreciated.

Answer 1

func underline(text: String, state: UIControlState = .normal, color:UIColor? = nil) {
        var titleString = NSMutableAttributedString(string: text)

        if let color = color {
            titleString = NSMutableAttributedString(string: text,
                               attributes: [NSForegroundColorAttributeName: color])
        }

        let stringRange = NSMakeRange(0, text.characters.count)
        titleString.addAttribute(NSUnderlineStyleAttributeName,
                                 value: NSUnderlineStyle.styleSingle.rawValue,
                                 range: stringRange)

        self.setAttributedTitle(titleString, for: state)
    }

Answer 2

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

Answer 3

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];

Answer 4

Nick's answer is a great, quick way to do this.

I added support in drawRect for shadows.

Nick's answer doesn't take into account if your button title has a shadow below the text:

But you can move the underline down by the height of the shadow like so:

CGFloat descender = self.titleLabel.font.descender;
CGContextRef contextRef = UIGraphicsGetCurrentContext();
CGFloat shadowHeight = self.titleLabel.shadowOffset.height;
descender += shadowHeight;

Then you'll get something like this:

Answer 5

Nick H247's answer but Swift approach:

import UIKit

class UnderlineUIButton: UIButton {

    override func drawRect(rect: CGRect) {
        super.drawRect(rect)

        let textRect = self.titleLabel!.frame

        var descender = self.titleLabel?.font.descender

        var contextRef: CGContextRef = UIGraphicsGetCurrentContext();

        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);
    }
}

Answer 6

It is very simple with attributed string

Creates a dictionary with set attributes and apply to the attributed string. Then you can set the attributed string as attibutedtitle in uibutton or attributedtext in uilabel.

NSDictionary *attrDict = @{NSFontAttributeName : [UIFont
 systemFontOfSize:14.0],NSForegroundColorAttributeName : [UIColor
 whiteColor]};
 NSMutableAttributedString *title =[[NSMutableAttributedString alloc] initWithString:@"mybutton" attributes: attrDict]; 
[title addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:NSMakeRange(0,[commentString length])]; [btnRegLater setAttributedTitle:title forState:UIControlStateNormal];