title: Make custom class of NSObject serializable
body: <p>I want a custom class based on NSObject to be serializable.
  I have read <a href="https://stackoverflow.com/questions/2182115/make-a-custom-class-serializable-in-objective-c-iphone">this</a> but want to ask some additional Qs.</p>
  
  <ol>
  <li>Does <code>NSObject</code> implement <code>NSCoder</code>? </li>
  <li>I also want to ask if I can serialize an array of some objects of this custom class that I want to be serializable. Does this require some special init?</li>
  <li>I know that I should implement <code>initWithCoder</code> and <code>encodeWithCoder</code>. Is it the variables in my custom object class that I should Encode/Decode there?</li>
  </ol>