转载自 ，略有改动

 

UnderLineButton.h代码

@interface UnderLineButton : UIButton+ (UnderLineButton *) underLineButton;@end

 

UnderLineButton.m代码

@implementation UnderLineButton- (id)initWithFrame:(CGRect)frame{    self = [super initWithFrame:frame];    if (self) {        // Initialization code    }    return self;}+ (UnderLineButton *) underLineButton {    UnderLineButton * button = [[UnderLineButton alloc] init];    return [button autorelease];}// An empty implementation adversely affects performance during animation.- (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+2.0f;    CGContextRef contextRef = UIGraphicsGetCurrentContext();        //set to same color 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