Resolved Multitasking Background Tasks

in app asynchronous downloads, trying implement multitasking allow background tasks complete, getting errors. in appdelegate didenterbackground:

code:

  application = [uiapplication sharedapplication]; //get shared application instance            __block uibackgroundtaskidentifier background_task; //create task object            background_task = [application beginbackgroundtaskwithexpirationhandler: ^ {          [application endbackgroundtask: background_task]; //tell system done tasks          background_task = uibackgroundtaskinvalid; //set task invalid                    //system shutting down app @ point in time      }];            //background tasks require use asyncrous tasks            dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^{          //perform tasks application requires                    nslog(@"\n\nrunning in background!\n\n");                    [application endbackgroundtask: background_task]; //end task system knows done need perform          background_task = uibackgroundtaskinvalid; //invalidate background_task      });  

i start download, , click home button. download doesn't terminate, doesn't keep going. once go app resumes. then, when app finished: if sent background @ point during download, following error in console:

code:

    2012-03-13 12:17:25.981 smcoc[16086:17f03] *** terminating app due uncaught exception 'nsunknownkeyexception', reason: '[<__nscfstring 0x10ce80f0> valueforundefinedkey:]: class not key value coding-compliant key response.'  *** first throw call stack:  

if allow download finish without ever entering background, fine.

 

the code posted looks should throw nslog , finish background task. there other code removed?

error seems unrelated background tasks. @ point seems code getting run this.

code:

  [someobject valueforkey:@"response"];  

and someobject variable nsstring. maybe trying reference invalid pointer happens point string?

 

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