title: Cannot connect UIButton to ViewController in XCode4
body: <p>I'm learning iPhone Dev and I'm stuck on something. I'm writing a simple calculator program, but when I try to connect one of the buttons on the calculator to the File Owner in Interface Builder I do not get any options:</p>
  
  <p>.h file</p>
  
  <pre><code>@interface CalculatorViewController : UIViewController
  {
  
      CalculatorBrain *brain;
      IBOutlet UILabel *label;
  
  }
  
  - (IBAction)digitPressed:(UIButton *)sender;
  
  - (IBAction)operandPressed:(UIButton *)sender;
  @end
  </code></pre>
  
  <p>.m file</p>
  
  <pre><code>#import "CalculatorViewController.h"
  
  @implementation CalculatorViewController
  
  - (IBAction)digitPressed:(UIButton *)sender
  {
      //not implemented yet
  }
  
  - (IBAction)operandPressed:(UIButton *)sender
  {
      //not implemented yet
  }
  @end
  </code></pre>
  
  <p>As far as I understand when I'm working with my CalculatorViewController.xib in interface builder if I try to connect a button to the file's owner I should have two options:
  1. digitPressed
  2. operandPressed</p>
  
  <p>However, I do not get any options. Any ideas what I'm doing wrong?</p>
  
  <p>Thanks.</p>