iOS开发：自定义带下划线文本的UIButton

Uiunderlinedbutton.h代码

@interface UIUnderlinedButton : UIButton {
}
+ (UIUnderlinedButton *) underlinedButton;
@end

Uiunderlinedbutton.m代码

@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