When the user types, where are the corresponding events sent? First, the window manager gets the event and forwards it to the active application. The active application forwards the keyboard events to the key window. The key window forwards the event to the “active” view. Which view, then, is the active one? Each window has an outlet called
firstResponder that points to one view of that window. That view is the “active” one for that window. For example, when you click on a text field, it becomes the
firstResponder of that window (Figure 16.1).
Figure 16.1. The First Responder of the Key Window Is “Active” ...