NSMutableAttributedString 的使用方法，设置格式

参考：http://blog.sina.com.cn/s/blog_a3dbd02a01012ixk.html

参考2：http://www.tuicool.com/articles/Fvqia2

NSMutableAttributedString *attrString =[[NSMutableAttributedStringalloc]initWithString:title];

    NSRange range = NSMakeRange(0, [attrString length]);

    

    [attrString beginEditing];

    [attrString addAttribute:NSLinkAttributeName value:aURL range:range];

    

   // make the text appear in blue

   [attrString addAttribute:NSForegroundColorAttributeNamevalue:[NSColorblueColor] range:range];

    

   // next make the text appear with anunderline

   [attrString addAttribute:NSUnderlineStyleAttributeNamevalue:[NSNumbernumberWithInteger:NSSingleUnderlineStyle]range:range];

    

   // allow truncation

   NSMutableParagraphStyle *ps = [[NSParagraphStyledefaultParagraphStyle] mutableCopy];

   [ps setLineBreakMode:NSLineBreakByTruncatingTail];

    [attrString addAttribute:NSParagraphStyleAttributeName value:ps range:range];

    [ps release];

    

    [attrString endEditing]；

  return [attrString autorelease];