Tewha.net https://tewha.net/tags/nsurlrequest/ Recent content on Tewha.net Hugo -- gohugo.io en-us Wed, 30 May 2012 14:00:00 +0000 Handling 302/303 redirects https://tewha.net/2012/05/handling-302303-redirects/ Wed, 30 May 2012 14:00:00 +0000 https://tewha.net/2012/05/handling-302303-redirects/ <p>If you try to POST to a web API using <code>NSURLConnection</code> that redirects you using a <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.3">302</a> or <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3.4">303</a> redirect, you’ll fall over to a GET request. This is intentional, but you can override it.</p> If you try to POST to a web API using NSURLConnection that redirects you using a 302 or 303 redirect, you’ll fall over to a GET request. This is intentional, but you can override it.

With HTTP status codes 302 and 303, the user agent (in this case, NSURLConnection) will change the request type from POST to GET. This is just how 302 was usually implemented; status code 303 was added to HTTP/1.1 to make this behaviour explicit.

HTTP/1.1 also added a status code to redirect without changing the request type from POST to GET. If you can change the web site, getting it to redirect you with a 307 instead will fix the problem.

If not, you can make NSURLRequest ignore this aspect of RFC2616.

NSURLRequest sends an event to its delegate, in which you can see what NSURLRequest plans to do and customize it:

- (NSURLRequest *)connection: (NSURLConnection *)connection
             willSendRequest: (NSURLRequest *)request
            redirectResponse: (NSURLResponse *)redirectResponse;
{
    if (redirectResponse) {
        NSMutableURLRequest *r = [[originalRequest mutableCopy] autorelease];
        [r setURL: [request URL]];
        return r;
    } else {
        return request;
    }
}

By doing this, you’re cloning the original request and changing the URL to match the request suggested by NSURLConnection (which is following the RFC).

See also:

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