iOS UILable的一些用法

1.按钮上的文字添加下划线

问题：实现下图中右侧的按钮文字效果

代码（绿色为按钮文字加下划线方法）：

    [MyTools createMyImageview:topEditView frame:CGRectMake(widthAll-90, 12, 17, 16) imageName:@"离线课程_下载更多.png"];
    UIButton *downMoreButton = [MyTools createMyBtn:@"下载更多" frame:CGRectMake(widthAll-70, 10, 60, 20) uiview:topEditView uifont:14 color:[UIColor colorWithRed:92/255.0 green:218/255.0 blue:231/255.0 alpha:1]];
    NSMutableAttributedString *title = [[NSMutableAttributedString alloc] initWithString:@"下载更多"];
    NSRange titleRange = {0,[title length]};
    [title addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:titleRange];
    [downMoreButton setAttributedTitle:title
                              forState:UIControlStateNormal];
    [downMoreButton.titleLabel setFont:[UIFont systemFontOfSize:14]];
    [downMoreButton addTarget:self action:@selector(downMore) forControlEvents:UIControlEventTouchUpInside];

 2.设置lable文字前后不同的颜色（参考：http://www.cocoachina.com/bbs/read.php?tid-282742-page-1.html）

UILabel *timeLabel = [[UILabel alloc]initWithFrame:CGRectMake(0, 10, 100, 20)];
timeLabel.font = [UIFont systemFontOfSize:10];
timeLabel.textColor = [UIColor blackColor];
NSMutableAttributedString *noteStr = [[NSMutableAttributedString alloc] initWithString:@"100:00/100:00"];
NSRange redRange = NSMakeRange(0, [[noteStr string] rangeOfString:@"/"].location);
[noteStr addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:redRange];
[timeLabel setAttributedText:noteStr] ;
//    [timeLabel sizeToFit];
[footView addSubview:timeLabel];