title: Facebook is not shown in UIActivityViewController but twitter does
body: <p>My iOS is 8.1.2 and I am using the UIActivityViewController for social sharing.
  I click on a button and allow the UIActivityViewController to present</p>
  
  <pre><code>- (IBAction)UIActivityTypeButtonClick:(id)sender {
  
  NSString* text=@"I am sharing this text";
  NSArray* sharedArray=@[text];
  UIActivityViewController * activityVC=[[UIActivityViewController alloc]initWithActivityItems:sharedArray applicationActivities:nil];
  activityVC.excludedActivityTypes=@[];
  [self presentViewController:activityVC animated:YES completion:nil];
  }
  </code></pre>
  
  <p>I am getting this </p>
  
  <p><img src="https://i.stack.imgur.com/7ne4B.png" alt="enter image description here"></p>
  
  <p>I am getting <strong>Message</strong>, <strong>Twitter</strong>, <strong>Mail</strong>, <strong>WhatsApp</strong> and a <strong>More</strong> button.
  <br>On clicking <strong>More</strong> I get this.</p>
  
  <p><img src="https://i.stack.imgur.com/B2tqo.png" alt="enter image description here">
  Where is <strong>FACEBOOK</strong>. I have the facebook app in my iPhone and it is setup with my ID too in settings. But facebook never shows up here. Twitter does. Is this a bug or what? Please suggest</p>
  
  <p>Thanks</p>