用NSAttributedString画下划线

UILabel *lable = [[UILabel alloc] initWithFrame:CGRectMake(20, 60, 100, 30)];

[self.view addSubview:lable];

lable.backgroundColor = [UIColor redColor];

lable.textAlignment = NSTextAlignmentCenter;

NSString *oldPrice = @"￥ 999999";

NSUInteger length = [oldPrice length];

[self.view addSubview:lable];

NSMutableAttributedString *attri = [[NSMutableAttributedString alloc] initWithString:oldPrice];

[attri addAttribute:NSStrikethroughStyleAttributeName value:@(NSUnderlinePatternSolid | NSUnderlineStyleSingle) range:NSMakeRange(0, length)];

[attri addAttribute:NSStrikethroughColorAttributeName value:[UIColor yellowColor] range:NSMakeRange(0, length)];

[lable setAttributedText:attri];