title: Why use "self" and what does it mean?
body: <p>So, I just started learning Objective-C and I've come across this "self" thing.  I've only ever used C, but I think it's used in java too maybe?  Can someone explain?  Here's an example:</p>
  
  <pre><code>- (IBAction)digitPressed:(UIButton *)sender
  {
      NSString *digit = [sender currentTitle];
      UILabel *myDisplay = [self display];  //why this?
  }
  </code></pre>
  
  <p>Why isn't it just this?</p>
  
  <pre><code>- (IBAction)digitPressed:(UIButton *)sender
  {
          NSString *digit = [sender currentTitle];
          UILabel *myDisplay = display;  //why not like this?
  }
  </code></pre>
  
  <p>display is a UILabel *</p>