iOS - background fetch and threads -


i have app, uses background fetch , update location during it. works fine code:

-(void)backgrounddidupdatelocations:(nsarray *)locations {         uiapplication *app = [uiapplication sharedapplication];     __block uibackgroundtaskidentifier locationupdatetaskid = [app beginbackgroundtaskwithexpirationhandler:     ^{         dispatch_async(dispatch_get_main_queue(),         ^{                         if (locationupdatetaskid != uibackgroundtaskinvalid)             {                  if (_backgroundfetchcompletionhandler != nil)                 {                     nslog(@"bg location finished 1");                     _backgroundfetchcompletionhandler(uibackgroundfetchresultnewdata);                     _backgroundfetchcompletionhandler = nil;                 }                  [app endbackgroundtask:locationupdatetaskid];                 locationupdatetaskid = uibackgroundtaskinvalid;             }         });     }];      dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0),     ^{                                 if (_delegate && [_delegate respondstoselector:@selector(mylocationmanager:didupdatelocations:)])         {             [_delegate mylocationmanager:self didupdatelocations:locations];         }          dispatch_async(dispatch_get_main_queue(),         ^{                         if (locationupdatetaskid != uibackgroundtaskinvalid)             {                 if (_backgroundfetchcompletionhandler != nil)                 {                     nslog(@"bg location finished 2");                     _backgroundfetchcompletionhandler(uibackgroundfetchresultnewdata);                     _backgroundfetchcompletionhandler = nil;                 }                  [app endbackgroundtask:locationupdatetaskid];                 locationupdatetaskid = uibackgroundtaskinvalid;             }         });     });  }

but there problem this:

[_delegate mylocationmanager:self didupdatelocations:locations];

if use simple call, fine. if _delegate method runs background operation, download data internet, have problem. download started asynchronously, background fetch "closed" backgroundfetchcompletionhandler before data delivered. data delivered outside of scope , afraid, can cause problems. how solve problem correctly?

edit: can not modify _delegate code, pass handler variable not option.

if delegate set , responds pass completion handler can work , call completion handler when it's done. if delegate isn't set or doesn't respond call completion handler directly.


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