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];