Building Cocoa Applications: A Step by Step Guide

Creating an Accessory NSView

An accessory view is an NSView that you provide to the NSSavePanel object. The NSSavePanel object is then automatically incorporated into the Save sheet when it is displayed. Many applications use accessory views to let the user choose options when saving.

IB has direct support for creating accessory views. It allows you to create standalone views — views that aren’t displayed in a window, but that are designed to be placed into windows as the need arises. In the next step, we’ll create a simple NSView instance that will be used as a container. We will then place the desired controls in this NSView and group it in a box. Finally, we will take the id of this view and pass it to the NSSavePanel object.

We’ll start by making the necessary changes to Controller.h. Then we’ll create the accessory view and make connections in IB. Finally, we’ll implement the necessary method in Controller.m to allow us to specify the file type.

1. Insert the formatBox and formatMatrix outlets and the savePanel instance variable into Controller.h:

   @interface Controller : NSObject
   {
       IBOutlet id graphView;
       IBOutlet id prefController;
       IBOutlet  id  formatBox;
                            IBOutlet  id  formatMatrix;
                            NSSavePanel  *savePanel;
   }

2. Insert the following setFormat: action method declaration into Controller.h:

                        - (IBAction)setFormat:(id)sender;

3. Save Controller.h.

4. Activate IB and make sure that MainMenu.nib is the active window.

5. Read (parse) the updated Controller class definition into MainMenu.nib.

   An easy ...