title: Add Instagram to UIActivityViewController
body: <p>I'm trying to share an image using standard <code>UIActivityViewController</code>, it's fine to share on <strong>Facebook</strong>, <strong>Twitter</strong> and <strong>Save Image</strong> using this code:</p>
  
  <pre><code>let firstActivityItem = "foo text"
  let secondActivityItem : UIImage = image!
  
  let activityViewController : UIActivityViewController = UIActivityViewController(
      activityItems: [firstActivityItem, secondActivityItem], applicationActivities: nil)
  
  activityViewController.excludedActivityTypes = [
      UIActivityTypePostToWeibo,
      UIActivityTypePrint,
      UIActivityTypeAssignToContact,
      UIActivityTypeAddToReadingList,
      UIActivityTypePostToVimeo,
      UIActivityTypePostToTencentWeibo
  ]
  
  self.presentViewController(activityViewController, animated: true, completion: nil)
  </code></pre>
  
  <p>I need one more thing, <strong>Instagram</strong>:</p>
  
  <pre><code>If UIApplication.sharedApplication().canOpenURL(instagramURL!) {
              // Success
              var img = image!
  
              var savePath: String = NSHomeDirectory().stringByAppendingPathComponent("Documents/Test.igo")
              UIImageJPEGRepresentation(img, 1).writeToFile(savePath, atomically: true)
              var imgURL = NSURL(string: NSString(format: "file://%@", savePath) as! String)
              docController = UIDocumentInteractionController(URL: imgURL!) // 1
              docController.UTI = "com.instagram.exclusivegram" // 2
              docController.delegate = self
              docController.annotation = ["InstagramCaption":"testsss"] // 3
              docController.presentOpenInMenuFromRect(self.view.frame, inView: self.view, animated: true) // 4
          } else {
              // Error
          }    
  </code></pre>
  
  <p>Both these codes work fine separately, how can I add <strong>Instagram</strong> to the <code>UIActivityViewController</code>? Is it possible at all?</p>