multithreading - Application UI hangs due to networking , iOS -

i developing ios application implementing push notifications.

in appdelegate , more in didregisterforremotenotificationswithdevicetoken function , after register push notifications , make http post request send server users credentials (cfuuid , os , etc..) , push token.

when server app goes smoothly. however , if reason server unreachable ui of application hangs around 30 seconds (till connection timeout) , thing see white screen.

how separate "networking" ui ? guess answer using thread.

how ? thing doing inside didregisterforremotenotificationswithdevicetoken use asihttprequest library send credentials server.

the code needs executed in different thread looks :

nsstring *jsonstring;     //jsonstring = [[nsstring alloc] initwithformat:@"{\"deviceuuid\":\"%@\",\"os\":\"ios\", \"active\":\"%d\", \"pushtoken\":\"%@\"}",deviceuuid,active,token];     jsonstring = [[nsstring alloc] initwithformat:@"{\"deviceuuid\":\"%@\",\"os\":\"ios\", \"pushtoken\":\"%@\"}",deviceuuid,token];     nslog(@"%@",jsonstring);      //nsstring *urlstr= [[nsstring alloc] initwithformat:cityinfo_server_url,@"push_notifications/register"];     nsstring *urlstr= [[nsstring alloc] initwithformat:cityinfo_server_url,@"register.php"];      //send json file , using asihttpclass     nsurl *url = [nsurl urlwithstring:urlstr];     asihttprequest *request = [asihttprequest requestwithurl:url];     request.timeoutseconds = time_out_seconds;     [request setrequestmethod:@"put"];      //nsstring *credentials= [self encodecredentials];     //[request addrequestheader:@"authorization" value:[[nsstring alloc] initwithformat:@"basic %@",credentials]];     [request addrequestheader:@"content-type" value:@"application/json; charset=utf-8"];       [request appendpostdata:[jsonstring datausingencoding:nsutf8stringencoding]];     [request startsynchronous];      if([request responsestatuscode]==200){         nslog(@"server reached. response status : 200");         return true;     } else {         nslog(@"server not reached");         return false; 

instead of sending synchronous request send asynchronous request

[request startasynchronous];  

and call method hitting service after time interval delegate method.