Open the MyTest program you created in the previous chapter.

Double-click the MainMenu.xib file stored in the Resources folder. Interface Builder appears, displaying your user interface window.

Choose Tools

Drag and drop the Radio Group anywhere on your user interface window. Two radio buttons initially appear.

Double-click the top radio button. The radio button's title appears highlighted.

Type Top and press Return.

Double-click the bottom radio button. When the radio button's title appears highlighted, type Bottom and press Return. (You may need to drag the side handle of the Radio Group so the radio button titles don't appear cut off.) Your user interface should display two radio buttons, similar to Figure 16-6.

Figure 16-6. The appearance of your user interface with two radio buttons added

Choose File

Switch to Xcode, click the MyTestAppDelegate.h file stored in the Classes folder, and modify the code as follows:

#import <Cocoa/Cocoa.h>

@interface MyTestAppDelegate : NSObject <NSApplicationDelegate> {

NSWindow *window;
}

@property (retain) IBOutlet NSWindow *window;

-(IBAction)findSelectedButton:(id)sender;

@end

Choose File

Click the MyTestAppDelegate.m file stored in the Classes folder and modify the code as follows:

#import "MyTestAppDelegate.h"

@implementation MyTestAppDelegate

@synthesize window;

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
    // Insert code here to initialize your application
}

- (void)dealloc {

    [window release];
    [super dealloc];
}

-(IBAction)findSelectedButton:(id)sender {
    NSButtonCell *selCell = [sender selectedCell];
    //NSLog (@"Title cell is %@", [selCell title]);
    NSLog (@"Title cell is %@", selCell.title);
}

@end

In the findSelectedButton method, you have a choice of how you want to access the radio button's title property. You can use the square bracket method like this:

[selCell title];

Or you can use the dot notation method like this:

selCel.title

Both methods are equivalent, but the dot notation method is preferred because it's simpler to understand.

Choose File

Double-click the MainMenu.xib file in the Resources folder. Interface Builder appears, displaying your user interface window with its two radio buttons.

Right-click the Radio Group. A heads-up window appears.

Move the mouse pointer over the circle that appears to the right of selector, under the Sent Actions category, and drag the mouse to the MyTest App Delegate icon, as shown in Figure 16-7.

Figure 16-7. Dragging the Radio Group's selector button connects it to your Objective-C method.

Release the mouse button while the mouse pointer is over the My Test App Delegate icon. A pop-up window appears, listing all the IBAction methods available in that class file.

Choose the findSelectedButton method.

Choose File

Switch to Xcode and click the Build and Run button or choose Build

Click the radio button named Bottom. Nothing will happen because the radio button is using the NSLog command to write to the log window.

Click the radio button named Top.

Quit your program by choosing MyTest

Choose Run

2010-09-18 12:15:39.772 UITest[22255:a0f] Title cell is Bottom
2010-09-18 12:15:40.927 UITest[22255:a0f] Title cell is Top

Double-click the radio button that you want to modify.

Choose Tools

Scroll down the Attributes Inspector window until you see the tag field under the Control category, as shown in Figure 16-8.

Figure 16-8. The Tag field appears under the Control category in the Attributes Inspector window.

Click in the tag field and type a number.

Repeat steps 1 to 4 for each radio button in the Radio Group. Be sure to give each radio button a unique tag value.