title: What is the bundle in the Objective-C?
body: <p>I downloaded the Facebook SDK, and I find there has something like <code>FBConnect.bundle</code> it is very interesting, and I also find some code is using the bundle, like this:</p>
  
  <pre><code>[loginButton setImage:
  [UIImage imageNamed:@"FBConnect.bundle/images/LoginWithFacebookNormal@2x.png"]
               forState:UIControlStateNormal];
  </code></pre>
  
  <p>So, I would like to know, what is the bundle? How can I know what inside the bundle? How can I create my own bundle? Thanks.</p>