To hook up the controller to the interface, you need to connect the button outlet in the controller to the red button in the interface:
1. Switch back to Interface Builder.
2. Select File’s Owner in the document window. File’s Owner represents the controller that will be managing the view. In this case, it points to the iShockUController class whose code you just edited.
3. Select Connections in the inspector window. Under the Outlets and Received Actions sections, you will see the outlets and actions you added to the controller code.
4. Next, you form connections between the controller code and the interface elements. Click and drag from the circle across from the button outlet, and release it over the button in the interface. ...