+ When you use XCode to write an Objective C application, + InterfaceBuilder can read the Objective C header files and use the + information in them to create descriptions of the classes in the + Objective C code. When the application is written in Lisp, + InterfaceBuilder can't read the class descriptions from the code, + and so we'll have to manually tell the nibfile about any classes + that we use in the user interface.
+As you will see in the following sections, we'll be using Lisp code to define two Objective C classes: Converter, and @@ -146,4 +154,8 @@ and the rest of the user interface.
+In InterfaceBuilder's Library window, select the Cocoa Objects and Controllers view:
@@ -164,5 +176,111 @@Now tell InterfaceBuilder the name of the new object's class. With the Object icon selected in the main CurrencyConverter window, - choose the Identity tab of the Inspector:
+ choose the Identity tab of the Inspector. At the top of the + Identity view is a "Class" field; type the name of your custom + class (in this case, "Converter") into the "Class" field and save + the nibfile: + +
+ Repeat the previous steps to create an instance of the + ConverterController class: drag an "Object" icon and drop it in the + main CurrencyConverter window. Then, change the name of the + Object's class to "ConverterController".
+ +That's all it takes to add an instance of a custom class to the + nibfile. We do still have to add the ConverterController class, and + we need to tell the nibfile a few more pieces of information about + the two classes—specifically, we need to add the names of + instance variables and actions, and we need to create the + connections between the instances.
+ +Now, using the "+" button below the "Class Outlets" section of the + Inspector, add outlets to the ConverterController class. The + outlets you need to add are named "amountField", "converter", + "dollarField", and "rateField".
+ +
+ We'll connect each of the "field" outlets to one of the text + fields in the CurrencyConverter UI, and we'll connect the + "converter" outlet to the Converter instance that we created + before. When the application launches, it creates the Converter and + ConverterController instances and establishes the connections that + we specify in the nibfile.
+ + +First, though, we need to tell the nibfile about actions as well as + outlets. With the "ConverterController" instance selected, use the + "+" button below the "Class Actions" section to add a new + action. Name the action "convert:":
+ +
+ In this application, the "convert:" action is the only action + defined for the user interface, so we are done. In more complex + applications you may need to define many actions and outlets.
+ +Now we'll connect outlets to objects and actions.
+ +InterfaceBuilder enables you to connect objects by + "Control-dragging" from one to another. To "Control-drag", you hold + down the Control key while dragging from one object to the next.
+ +Select the "ConverterController" instance in the nibfile's main + window, and Control-drag a connection to the "Exchange rate" text + field in the application's main window. When you release the mouse + button, InterfaceBuilder pops up a menu that lists the available + outlets. Choose "rateField" from the menu. The "rateField" outlet + of the "ConverterController" instance is now connected to the + "Exchange rate" text field.
+ +Repeat the same steps for the "Dollars" field and the "Amount" + field, connecting them to the "dollarField" and "amountField" + outlets, respectively.
+ +Finally, Control-drag a connection from the "ConverterController" + instance to the "Converter" instance. Choose "converter" from the + popup menu to connect the "converter" field of the + "ConverterController" instance to the "Converter" instance.
+ +To confirm that the connections are correct, you can use the + Connections view in the inspector. With the "ConverterController" + instance selected, click the blue arrow icon at the top of the + Inspector window to display connections. You should see a list of + outlets and the types of objects they are connected to:
+ +
+ We need to add one more connection: from the "Convert" button in + the application window to the "ConverterController" + instance. Control drag a connection from the "Convert" button to + the "ConverterController" instance. InterfaceBuilder pops up a + menu; choose the "convert:" action from the menu to connect the + button to the action.
+ +The nibfile now contains descriptions of the needed cusstom + classes and their connections. You can continue with the next + section, which explains how to write the Lisp code that implements + the application's behavior.