iPhone SDK: URL request not timing out.

Question

I am having a problem with a network request that should timeout, but the method is not called. The request is as follows:

#define kCONNECT_TIMEOUT 20.0

request = [NSMutableURLRequest requestWithURL: aUrl];
[request setHTTPMethod: @"POST"];
postData = [jsonData dataUsingEncoding:NSASCIIStringEncoding];
[request setHTTPBody:postData];
[request setValue:@"text/xml" forHTTPHeaderField:@"Accept"];
[request setValue:@"application/json" forHTTPHeaderField:@"Content-Type"]; 
[request setCachePolicy:NSURLCacheStorageAllowed];
[request setTimeoutInterval:kCONNECT_TIMEOUT];
self.connection = [NSURLConnection connectionWithRequest:request delegate:self];
assert(self.connection != nil);

This should get a callback to

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)_error 

But after 4 minutes no error message is displayed. Anyone know why this might be?

Answer 1

If you want better timeout management on http requests using NSURLConnection then it is much better to run the request asynchronous together with an NSTimer that can cancel the NSURLConnection when it fires because the timeout period expired.

This also means you don't have to deal with threads, which is generally a good idea. Async event (runloop) based operations are the way to go in 99.9% of the cases on the iPhone.

Answer 2

A representative from Apple has divulged that SDK 3.0 and later enforce a minimum timeout of (you guessed it) four minutes:

https://devforums.apple.com/thread/25282

If you try to set a timeout value of less than 240 seconds, it gets clamped up to 240. If you need a shorter timeout, I cast my vote for St3fan's solution.