ios - NSURLSessionDataTask timeout subsequent requests failing -

i creating nsmutablerequest:

self.req = [nsmutableurlrequest requestwithurl:myurl cachepolicy:nsurlrequestreloadignoringcachedata timeoutinterval:10.0]; 

the timeout set 10 seconds because don't want user wait long feedback. after create nsurlsessiondatatask:

nsurlsessiondatatask *task = [self.session datataskwithrequest:self.req completionhandler:^(nsdata *data, nsurlresponse *response, nserror *error) {     nshttpurlresponse * httpresp = (nshttpurlresponse *)response;     if (error) {         // timeout     }      else if (httpresp.statuscode < 200 || httpresp.statuscode >= 300) {         // handling error , giving feedback     }      else {         nserror *serializationerror = nil;         nsdictionary *jsondict = [nsjsonserialization jsonobjectwithdata:data options:kniloptions error:&serializationerror];     }     [task resume]; } 

the problem server goes gateway timeout , takes lot of time. timeout error , give feedback user, following api calls fail in same way due timeout error. way stop kill app , start over. there should kill task or connection after timeout error? if don't set timeout , wait until receive error code server following calls work (but user waits lot!).

i tried cancel task:

nsurlsessiondatatask *task = [self.session datataskwithrequest:self.req completionhandler:^(nsdata *data, nsurlresponse *response, nserror *error) {     nshttpurlresponse * httpresp = (nshttpurlresponse *)response;     if (error) {         // timeout         [task cancel];     }      ...     [task resume]; } 

i didnt see resume task started. need declare:

[task resume]; 

this line resumes task, if suspended.

try call nsurlsession follows:

[nsurlsession sharedsessison] instead of self.session 

and invalidate session by:

 [[nsurlsession sharedsession]invalidateandcancel]; 

from apple's documentation:

when app no longer needs session, invalidate calling either invalidateandcancel (to cancel outstanding tasks) or finishtasksandinvalidate (to allow outstanding tasks finish before invalidating object).

    - (void)invalidateandcancel 

once invalidated, references delegate , callback objects broken. session objects cannot reused.

to allow outstanding tasks run until completion, call finishtasksandinvalidate instead.

  - (void)finishtasksandinvalidate 

this method returns without waiting tasks finish. once session invalidated, new tasks cannot created in session, existing tasks continue until completion. after last task finishes , session makes last delegate call, references delegate , callback objects broken. session objects cannot reused.

to cancel outstanding tasks, call invalidateandcancel instead.