UILabel和UIButton添加下划线

关于UILabel和UIButton有的时候需要添加下划线，一般有两种方式通过默认的 NSMutableAttributedString设置，第二种就是在drawRect中画一条下划线，本文就简单的选择第一种，第二种有兴趣的可以自己研究一下。

UILabel设置下划线:

UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(10, 100, 310, 50)];
    label.backgroundColor = [UIColor redColor];
    [label setLineBreakMode:NSLineBreakByWordWrapping];
    label.numberOfLines =3;
    [label setFont:[UIFont systemFontOfSize:14]];
    NSMutableAttributedString *content = [[NSMutableAttributedString alloc]initWithString:[NSString stringWithFormat:@"博文地址:http://www.cnblogs.com/xiaofeixiang 博客园-FlyElephant QQ群:228407086"]];
    NSRange contentRange = {0,[content length]};
    [content addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:contentRange];

label.attributedText = content;
[self.view addSubview:label];</pre><br>

UIButton设置下划线:

UIButton *button=[[UIButton alloc]initWithFrame:CGRectMake(10, 200, 80, 30)]; 
    NSMutableAttributedString *title = [[NSMutableAttributedString alloc] initWithString:@"FlyElephant"]; 
    NSRange titleRange = {0,[title length]}; 
    [title addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:titleRange]; 
    [button setAttributedTitle:title 
                      forState:UIControlStateNormal]; 
    [button setBackgroundColor:[UIColor redColor]]; 
    [button.titleLabel setFont:[UIFont systemFontOfSize:14]]; 
    [self.view addSubview:button];