1.label设置行间距或者段间距 还有两端对齐方式（label没有该属性）
2.label给指定字符串显示指定的颜色、字体大小。下划线等。

代码

 //message

 NSMutableAttributedString * attributedString = [[NSMutableAttributedString alloc] initWithString:_message];
//样式
 NSMutableParagraphStyle * paragraphStyle = [[NSMutableParagraphStyle alloc] init];
 //设置label每行文字之间的行间距   paragraphStyle.lineSpacing=3;
//设置文字两端对齐
paragraphStyle.alignment=NSTextAlignmentJustified;
 NSDictionary * dic =@{
                          //这两个一定要加哦。否则就没效果啦
                          NSParagraphStyleAttributeName:paragraphStyle,
                          
                          NSUnderlineStyleAttributeName:[NSNumber numberWithInteger:NSUnderlineStyleNone],
                          NSFontAttributeName:[UIFont systemFontOfSize:14]
                          
                          };
 //富文设置样式                      
 [attributedString setAttributes:dic range:NSMakeRange(0, attributedString.length)];
                          
 //设置                          
  _labelmessage.attributedText = attributedString;

计算高度

     CGSize titleSize = [mStr boundingRectWithSize:CGSizeMake(SCREEN_WIDTH - 16 * 2, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin context:nil].size;