什么时候NSURLResponse不是NSHTTPURLResponse？

问题描述

我见过很多代码，包括Apple的SimpleURLConnections示例，它只是将NSURLResponse转换为NSHTTPURLResponse。如果它始终是NSHTTPURLResponse为什么NSURLConnections不返回NSHTTPURLResponse？

I've seen a lot of code, including Apple's SimpleURLConnections sample, that simply cast any NSURLResponse to a NSHTTPURLResponse. If it is always a NSHTTPURLResponse why do the NSURLConnections not return NSHTTPURLResponse?

我担心如果我简单地转发响应，我会引入错误的代码。

I'm worried that if I simply downcast the response, I'm introducing buggy code.

例如，如果不检查isKindOfClass就可以吗？

For instance, is it OK to do this without checking isKindOfClass?

- (NSURLRequest *)connection:(NSURLConnection *)connection willSendRequest:(NSURLRequest *)request redirectResponse:(NSURLResponse *)redirectResponse
{
 NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse*)redirectResponse;
 // do stuff
}

推荐答案

如果您确定您的连接是通过HTTP协议运行的，那就没关系了：

It is ok if you are sure that your connection runs via HTTP protocol:

例如，如果您通过FTP连接，然后将 NSURLResponse 转换为 NSHTTPURLResponse 将不正确。

If you are connecting via FTP, for example, then casting NSURLResponse to NSHTTPURLResponse will be incorrect.

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