title: Attempt to present UIImagePickerController on UITabBarController while a presentation is in progress
body: <p>I need help for resolving a warning error. I use a <code>UIImagePickerController</code> and it's showing when I tap on the third tab on my tabBar. When I cancel, I want to show the last tab before the selection of the camera, but when I dismiss my picker, I get a warning!!</p>
  
  <p>This is my code and I don't understand why I get the warning...</p>
  
  <pre><code>-(void)viewWillAppear:(BOOL)animated{
      [super viewWillAppear:animated];
      [self showPickerController];
  }
  
  
  - (void) showPickerController
  {
      imagePicker = [[UIImagePickerController alloc] init];
      if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
          imagePicker.sourceType = UIImagePickerControllerSourceTypeCamera;
          imagePicker.delegate = self;
      } else{
          UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Erreur !"
                                                            message:@"Votre iPhone n'a pas de Camera"
                                                           delegate:self
                                                  cancelButtonTitle:@"Ok"
                                                  otherButtonTitles:nil];
          [message show];
      }
      [self presentViewController:imagePicker animated:NO completion:nil];
  }
  
  #pragma mark - Camera Methods
  
  - (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
      [self.tabBarController dismissViewControllerAnimated:NO completion:^{
          if(self.tabBarController!=nil)
              [self.tabBarController setSelectedIndex:0];
      }];
  }
  </code></pre>
  
  <p>Any idea?</p>