UILabel设置下划线:

UILabel*label=[[UILabelalloc]initWithFrame:CGRectMake(10,100,310,50)];label.backgroundColor=[UIColorredColor];[labelsetLineBreakMode:NSLineBreakByWordWrapping];label.numberOfLines=3;[labelsetFont:[UIFontsystemFontOfSize:14]];NSMutableAttributedString*content=[[NSMutableAttributedStringalloc]initWithString:[NSStringstringWithFormat:@"博文地址:http://www.cnblogs.com/xiaofeixiang博客园-FlyElephantQQ群:228407086"]];NSRangecontentRange={0,[contentlength]};[contentaddAttribute:NSUnderlineStyleAttributeNamevalue:[NSNumbernumberWithInteger:NSUnderlineStyleSingle]range:contentRange];label.attributedText=content;[self.viewaddSubview:label];

UIButton设置下划线:

UIButton*button=[[UIButtonalloc]initWithFrame:CGRectMake(10,200,80,30)];NSMutableAttributedString*title=[[NSMutableAttributedStringalloc]initWithString:@"FlyElephant"];NSRangetitleRange={0,[titlelength]};[titleaddAttribute:NSUnderlineStyleAttributeNamevalue:[NSNumbernumberWithInteger:NSUnderlineStyleSingle]range:titleRange];[buttonsetAttributedTitle:titleforState:UIControlStateNormal];[buttonsetBackgroundColor:[UIColorredColor]];[button.titleLabelsetFont:[UIFontsystemFontOfSize:14]];[self.viewaddSubview:button];