title: Does System.get_property('phone_id') always return a value?
body: <p>The <a href="http://rhodesapi.rhomobile.com/system-api#getproperty" rel="nofollow">documentation</a> says nothing about possible return values. I have looked for the implementation in the <a href="https://github.com/rhomobile/rhodes" rel="nofollow">source code</a>, but I am unable to find it.</p>
  
  <p>I wrote a simple application and ran it in the iPhone Simulator, but no value is shown. The application was created by running <code>rhogen app phone_id</code>. I then added the following line to the <code>app/application.rb</code> file just before the call to <code>super</code>:</p>
  
  <pre><code>@phoneId = System.get_property('phone_id')
  </code></pre>
  
  <p>Then I added this line to <code>app/index.erb</code>:</p>
  
  <pre><code>&lt;p&gt;Phone id = &lt;span&gt;&lt;%= @phoneId %&gt;&lt;/span&gt;&lt;/p&gt;
  </code></pre>
  
  <p>I know that the simulator will return a unique identifier because I wrote an actual iOS application that merely writes the unique identifier to a label with the following bit of code:</p>
  
  <pre><code>[idLabel setText:[[UIDevice currentDevice] uniqueIdentifier]];
  </code></pre>
  
  <p>Since I don't know Ruby, and I particularly don't know Rhodes, I am unsure if the Rhodes test application I wrote is working correctly. So, I don't know if the call to <code>System.get_property</code> is working as it should or if it should really be returning an identifier.</p>
  
  <p>Thus my question, does <code>System.get_property('phone_id')</code> always return a value? If so, is that value guaranteed to be unique? Or are there cases where the method will return <code>nil</code>?</p>