title: Testing for nil in Objective-C -- if(x != nil) vs if(x)
body: <p>Most of the examples I found on the net write this:</p>
  
  <pre><code>if(x != nil)
      // ...
  </code></pre>
  
  <p>Is there any problems with this?</p>
  
  <pre><code>if(x)
      // ...
  </code></pre>
  
  <p>I tried both in a simple program and couldn't found any difference.</p>