title: Private interface vs. private method - objective c
body: <p>What is the difference between a private method and a private interface?
  For example, I know that if you define a method in an implementation and its interface does not mention it, it is considered a private method.  I have also seen things such as:</p>
  
  <pre><code>@interface Collector()
  @property (readonly) NSMutableDictionary *count;
  @end
  </code></pre>
  
  <p>Inside of the .m implementation file.</p>