cocoa-touch – 如何从短网址获取长网址

我想确定一个短网址的长网址是什么.我尝试过使用http HEAD请求,但很少有返回的头字段实际上包含与destination / long url相关的任何数据.

在那儿：
1.有什么方法可以确定长网址吗？
2.如果是这样,可以在不下载目的地主体的情况下完成吗？

谢谢

执行HEAD并查找Location标头.

% telnet bit.ly 80
Trying 168.143.173.13...
Connected to bit.ly.
Escape character is '^]'.
HEAD /cwz5Jd HTTP/1.1
Host: bit.ly

HTTP/1.1 301 Moved
Server: nginx/0.7.42
Date: Fri, 12 Mar 2010 18:37:46 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Set-Cookie: _bit=4b9a89fa-002bd-030af-baa08fa8;domain=.bit.ly;expires=Wed Sep  8 14:37:46 2010;path=/; HttpOnly
Location: http://www.engadget.com/2010/03/12/motorola-milestone-with-android-2-1-hitting-bulgaria-by-march-20/?utm_source=twitterfeed&utm_medium=twitter
MIME-Version: 1.0
Content-Length: 404