title: set controls properties at main uiview from other uiview
body: <p>I have main controller: </p>
  
  <pre><code>@interface BallsViewController : UIViewController
  @property (weak, nonatomic) IBOutlet UILabel *InfoLabel;
  @property (weak, nonatomic) IBOutlet UIButton *nextBallButton;
  @property (weak, nonatomic) IBOutlet ViewBoard *viewBoard;
  
  - (IBAction)addNextBalls:(id)sender;
  
  @end
  </code></pre>
  
  <p>ViewBoard is UiView on which I draw. Sometimes I want to send to controller information that user can not draw anymore. This information will be set to label and button used to draw should be disabled.</p>
  
  <p>How can I achieve that in proper mvc way ?</p>