Learning Cocoa

Define the Classes of Travel Advisor

Travel Advisor has three classes: Country, Converter, and TAController. Only TAController has outlets and actions. And, rather than defining the Converter class, you are simply going to add it to the project from the Currency Converter project and reuse it.

Specify the Country and TAController Classes

Subclass NSObject to create the Country and TAController classes.

1. In Interface Builder, bring up the Classes display of the nib file window.

2. Select NSObject as the superclass.

3. Choose Subclass from the Classes menu.

4. Type Country in place of MyObject.

5. Repeat for TAController.

Specify TAController’s Outlets and Actions

Now that the interface has been laid out, you can define the outlets that let TAController communicate with the UI objects. While here, you can also add the outlet for the Converter object that will be reused from the Currency Converter project.

1. Select TAController and choose Add Outlet from the Classes menu.

2. Add the following outlets:

   celsiusField

   commentsField

   commentsLabel

   converter

   countryField

   countryTableView

   currencyDollarsField

   currencyLocalField

   currencyNameField

   currencyRateField

   englishSpokenSwitch

   fahrenheitField

   languagesField

   logisticsForm

In addition to outlets, you must specify actions so that the UI objects can message TAController.

1. Select TAController and choose Add Action from the Classes menu:

2. Define the following action methods:

   addRecord:

   blankFields:

   convertCurrency:

   convertTemp:

   deleteRecord:

   handleTVClick: ...