title: What are the possible values for contentURL when using Kik iOS SDK?
body: <p>I'm trying to send a message via Kik from my iOS app, and I use official <a href="https://github.com/kikinteractive/kik-api-iphone" rel="nofollow">Kik SDK</a> for that.
  Specifically, the message should contain URL/link for the certain app on the Apple's app store.</p>
  
  <p>This is the code:</p>
  
  <pre><code>    KikMessage *message = [KikMessage articleMessageWithTitle:@"Title of your Article"
                                                           text:@"Check it out!"
                                                     contentURL:@"https://itunes.apple.com/us/app/idXXXX?mt=8"
                                                     previewURL:@""];
      [[KikClient sharedInstance] sendKikMessage:message];
  </code></pre>
  
  <p>It works to the moment I try to open URL I've sent. For some URLs (ex: <code>@"http://google.com"</code> it works good - it opens a pop-up with the appropriate content of that page.</p>
  
  <p>But if change it to <code>@"https://itunes.apple.com/us/app/idXXXX?mt=8"</code>, Kik shows the error: </p>
  
  <blockquote>
    <p>Unknown Content
    No action associated with this content</p>
  </blockquote>
  
  <p>Changing protocol to <code>http</code> and to <code>itms-apps://itunes.apple.com/app/idXXXXX</code> doesn't help either.</p>
  
  <p>I'm wondering if there are any requirements for that URL or its content, any restrictions on it? Is it possible to send user a link to the app store?</p>
  
  <p>ps: it probably doesn't matter, but despite the docs, previewURL is not optional - it cannot be nil, and the empty string is passed, as a workaround.</p>