title: iPhone file extension app association
body: <p>On my iPhone, I'm running an app called Caissa Chess. After registering the app with the manufacturer (this is optional) I received an email, containing a chess puzzle. The crucial part of the mail message, showing a chess diagram looks like this:</p>
  
  <pre><code>&lt;a href="chess://puzzle/8/p1R3p1/4p1kn/3p3N/3Pr2P/6P1/PP3K2/8 w ?term=w2&amp;solution=c7xg7&amp;description=Amura%20vs%20Carlos%20Bulcourf%2C%20Villa%20Ballester%2C%201996"&gt;&lt;img src="cid:image1"&gt;&lt;/a&gt;
  </code></pre>
  
  <p>Tapping the diagram displayed by this URL quits Mail.app and opens Caissa Chess, that then displays the diagram, and allows you to solve the puzzle.</p>
  
  <p>How does this work?I want to make a little app for the iPhone, that will need an external file, sent by email. I will fist need to understand what's going on.</p>
  
  <ul>
  <li><code>chess://</code> how and where is defined what application will be opened? </li>
  <li>what does the rest of the URL mean? Would it be referring to a local file, or will it be resolved by the app as a live http: url? The email message body contains an image attachment.</li>
  </ul>
  
  <p>I'm sure that this mechanism is documented somewhere, but the books I have don't describe it, and Google didn't help me either.</p>
  
  <p>Thank you in advance</p>
  
  <p>Sjakelien</p>