title: Use UIActivityViewController to trigger action inside my own app
body: <p>In my app, I have implemented an iPhone-to-iPhone sharing method, which I will call 'Beamer' for now.</p>
  
  <p>For sharing stuff through Mail, FB, etc, I use the UIActivity View Controller.
  For a logical workflow, I would like to share Beamer from that sheet as well.</p>
  
  <p>When you share through Mail, you are prompted with a modal dialog, allowing you to assign recipients, type some body text, etc.</p>
  
  <p>I want something like that for Beamer as well: a custom dialog, modal is fine, where the user can do some last minute interaction.
  Is such possible? Studying some code, I think the</p>
  
  <pre><code>- (void) performActivity {}
  </code></pre>
  
  <p>is intended to do that, but so far I have only found references to external apps.
  How do I refer to my own app? And how do I pass on parameters?</p>