响应expectedContentLength返回-1 [英] response expectedContentLength return -1

问题描述

你好我需要在从我的webservice加载数据时创建一个progressView。

Hello i need to create a progressView when i load data from my webservice.

实际上，expectedContentLength总是返回-1。

Actually the expectedContentLength alway return -1.

看了很多类似的问题之后，看起来我的webservice从未发送Content-Length：。

After look lots of similary problem it looks like my webservice never send the Content-Length:.

然后我检查CURL，这是结果：

Then i check with CURL and here is the result :

< HTTP/1.1 200 OK
< Date: Thu, 21 Jun 2012 10:04:39 GMT
< Server: Apache/2.2.16 (Debian)
< X-Powered-By: PHP/5.3.3-7+squeeze9
< cache-control: no-cache
< Vary: Accept-Encoding
< Content-Type: text/html; charset=UTF-8
< Content-Length: 3239  
< Connection: Keep-Alive
< Set-Cookie: PHPSESSID=u4o4i9dofdgnkfmtnf163635j6; path=/

这是我的代码来捕捉长度

and here is my code to catch length

long long expectDataSize;
long long currentDataSize;

....

 - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSHTTPURLResponse *)response
{
    NSLog(@"expect content length %lld", [response expectedContentLength]);
    expectDataSize = [response expectedContentLength];
    currentDataSize = 0;
}

任何人都已经看到这个问题？

Anyone have already see this problem ?

推荐答案

好的我自己解决这里是我真正的问题和解决方案：

Ok i've fix it myself here is my real problem and a solution :

当我问与Curl我可以得到长度没问题。

When i ask with Curl i can get the length no problem.

但是当我使用NSurlConnection时

But when i use NSurlConnection

NSURLConnection *c = [[NSURLConnection alloc] initWithRequest:req delegate:self];

响应将使用Gzip进行压缩（不要问我原因）。如果响应是用Gzip编码的，则无法知道长度，然后 expectedContentLength 返回 -1 。
[response allHeaderFields] 中没有内容长度。

The response will be compress with "Gzip" (don't ask me why). And if the response is encode with Gzip it's impossible to know the length, then "expectedContentLength" return -1. And "Content-Length" is absent from [response allHeaderFields].

如果你真的想要获得长度，你可以只需强制不要像这样使用Gzip：

If you really want to get the length you can simply force to not use Gzip like this :

[req setValue:@"" forHTTPHeaderField:@"Accept-Encoding"];

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