title: warning: Attempt to present modal when notification is called
body: <p>i am calling <code>presentModal</code> method on <code>viewDidAppear</code> using :</p>
  
  <pre><code>[[NSNotificationCenter defaultCenter] addObserver:self         
                                               selector:@selector(presentModal)         
                                                   name:@"xxxxxxx"         
                                                 object:nil];
  
  -(void)presentModal 
  {
      PickerModalViewController *pickerModalViewController = [Appdelegate.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:@"PickerModalViewController"];
  
      pickerType = 2;
      pickerModalViewController.choices = self.localArray;
      pickerModalViewController.buttonTag = pickerType;
  
      pickerModalViewController.delegate = self;
      self.pickerPresenter = self;
  
      if (self.pickerPresenter) {
          [self.pickerPresenter presentViewController:pickerModalViewController animated:YES completion:nil];
      }
  }
  </code></pre>
  
  <p>when picker is presented it gives me a waring in both device and simulator </p>
  
  <p>Warning: <code>Attempt to present PickerModalViewController: 0x10ec7280  on     UINavigationController: 0x90ad610 while a presentation is in progress!</code></p>