title: Change Action sheet popover arrow in iOS8
body: <p>i'm using <code>UIAlertController</code> . But on iPad with iOS 8, actionSheet show with popover arrow. Any ideas to hide that arrow? </p>
  
  <p>Here is my code:</p>
  
  <pre><code>UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"this is alert controller" message:@"yeah" preferredStyle:UIAlertControllerStyleActionSheet];
  
              UIAlertAction *cancelAction = [UIAlertAction
                                             actionWithTitle:NSLocalizedString(@"Cancel", @"Cancel action")
                                             style:UIAlertActionStyleCancel
                                             handler:^(UIAlertAction *action)
                                             {
                                                 NSLog(@"Cancel action");
                                             }];
  
              UIAlertAction *okAction = [UIAlertAction
                                         actionWithTitle:NSLocalizedString(@"OK", @"OK action")
                                         style:UIAlertActionStyleDefault
                                         handler:^(UIAlertAction *action)
                                         {
                                             NSLog(@"OK action");
                                         }];
  
              UIAlertAction *deleteAction = [UIAlertAction
                                             actionWithTitle:NSLocalizedString(@"Delete", @"Delete action")
                                             style:UIAlertActionStyleDestructive
                                             handler:^(UIAlertAction *action) {
                                                 NSLog(@"Delete action");
                                             }];
  
              [alertController addAction:cancelAction];
              [alertController addAction:okAction];
              [alertController addAction:deleteAction];
  
              UIPopoverPresentationController *popover = alertController.popoverPresentationController;
              if (popover) {
                  popover.sourceView = self.view;
                  popover.sourceRect = self.view.bounds;
                  popover.permittedArrowDirections = UIPopoverArrowDirectionUnknown;
              }
              [self presentViewController:alertController animated:YES completion:nil];
  </code></pre>