Adding the Nib File that Specifies the Carbon Interface

To add the nib file that specifies the Carbon interface, do the following:

1. Open the Xcode project for your Cocoa application.

2. Choose Project > Add Files.

3. Locate the nib file you just created and double-click its name.

4. Click Add in the dialog that appears.

   If your Cocoa application has more than one target, you need to choose the appropriate target before you click Add.

Declaring the Interface for the Controller

Your controller for the CarbonInCocoa application has two instance variables: a WindowRef structure for the Carbon window and an NSWindow object. The NSWindow object allows management of the Carbon window using Cocoa methods. (See Showing the Carbon Window.)

The sample application’s controller has no other instance variables, but your application would need to declare any other instance variables that are appropriate. Listing 1 shows the declaration for the controller in the CarbonInCocoa application.

Listing 1  The declaration for the controller

@interface MyController : NSObject

{

    WindowRef   window;

    NSWindow    *cocoaFromCarbonWin;

}

@end

Loading the Nib File

The Cocoa nib file is loaded automatically when the Cocoa application is launched; however, you must explicitly load the nib file that contains the Carbon interface. For the CarbonInCocoa application, the nib file is loaded when the user clicks the Show Carbon Window button in the Cocoa window.

Listing 2 shows the code needed to load the Carbon nib file at runtime. An explanation of each numbered line of code appears following the listing.

Listing 2  Loading a nib file for a Carbon window

    CFBundleRef bundleRef;

    IBNibRef    nibRef;

    OSStatus    err;

    bundleRef = CFBundleGetMainBundle();                                // 1

    err = CreateNibReferenceWithCFBundle (bundleRef,

                    CFSTR("SampleWindow"),

                    &nibRef);                                          // 2

    if (err!=noErr)

                NSLog(@"failed to create carbon nib reference");

    err = CreateWindowFromNib (nibRef,

                            CFSTR("CarbonWindow"),

                            &window);                                  // 3

    if (err!=noErr)

                NSLog(@"failed to create carbon window from nib");

    DisposeNibReference (nibRef);                                       // 4

Here’s what the code does:

1. Calls the Core Foundation opaque type CFBundle function CFBundleGetMainBundle to obtain an instance of the application's main bundle. You need this reference for the next call.

2. Calls the Interface Builder Services function CreateNibReferenceWithCFBundle to create a reference to the Carbon window’s nib file. The Core Foundation string you provide must be the name of the nib file, but without the .nib extension.

3. Calls the Interface Builder Services function CreateWindowFromNib to unarchive the Carbon window from the nib file. On return, window is a WindowRef to the Carbon window. Recall from Declaring the Interface for the Controller that window is a controller instance variable.

4. Calls the Interface Builder Services function DisposeNibReference to dispose of the reference to the nib file. You should call this function immediately after you have finished unarchiving an object.

Creating an NSWindow Object for the Carbon Window

You do not need to create an NSWindow object for the Carbon window; however, doing so lets you use Cocoa methods rather than Carbon functions to manage the Carbon window, which may be desirable in some applications and is what the CarbonInCocoa application does.

You can create an NSWindow object for a Carbon window by allocating an NSWindow object and then initializing the object using the initWithWindowRef: method, as shown in the following line of code:

cocoaFromCarbonWin = [[NSWindow alloc] initWithWindowRef:window];

Recall from Loading the Nib File that window is a reference to the Carbon window.

You can find more information about the NSWindow object and the initWithWindowRef: method in NSWindow Class Reference.

Showing the Carbon Window

Because you created an NSWindow object for the Carbon window, you can call the makeKeyAndOrderFront: method to show the window instead of calling the Carbon function ShowWindow. You show the Carbon window with the following line of code:

 [cocoaFromCarbonWin makeKeyAndOrderFront:nil];