Call Web Service when receiving silent push notification?

Question

I have following code:

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler
{
  NSLog(@"Silent notification %@", userInfo);
  if([userInfo[@"aps"][@"content-available"] intValue]== 1) //it's the silent notification
  {
    NSLog(@"It is 1!");
    [self callWebService];

    completionHandler(UIBackgroundFetchResultNewData);
    return;
  }
  else
  {
    NSLog(@"It is not 1!");
    completionHandler(UIBackgroundFetchResultNoData);
    return;
  }
}

#pragma mark - Web Service
- (void)callWebService {
  NSLog(@"call web service");
  cdata_branches=[NSMutableData data];

  NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
  [request setURL:[NSURL URLWithString:[NSString stringWithFormat:someURL]]];
  conn=[[NSURLConnection alloc] initWithRequest:request delegate:self];
}

#pragma mark -
#pragma mark Connection

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response{
  [cdata_branches setLength:0];
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
  [cdata_branches appendData:data];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {

}

- (void)connectionDidFinishLoading:(NSURLConnection *)connection {
  NSString *s_json=[[NSString alloc] initWithData:cdata_branches encoding:NSUTF8StringEncoding];
  NSLog(@"connectionDidFinishLoading JSON data=\n%@",s_json);

  UIAlertView *alertView;
  alertView = [[UIAlertView alloc] initWithTitle:@"Success"
                                         message:[s_json substringWithRange:NSMakeRange (25, 50)]
                                        delegate:nil
                               cancelButtonTitle:@"OK"
                               otherButtonTitles:nil];
  [alertView show];
}

I am able to get the silent PN, however, the call web service seems failed, because it doesn't go to - (void)connectionDidFinishLoading:(NSURLConnection *)connection .

Anyone knows what could be wrong?

Note:

The web service 100% works if called from - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

Answer 1

Enable background fetch in Application background modes.

Enable Remote notifications in Application background modes.

Remote notifications is a special (and rather poorly named) background mode that allows the app to download content in response to a push notification.

You will have 30 seconds to complete your data fetching. Finally call completion handler when the fetching is done.