Question

I have started a project in Xcode 3.x using the “Create a Window-Based Application” option. The project seems to load the main nib file by itself from the info.plist entry : “Main nib file base name”.

Now I wish to load the main nib file using a UIViewController. Can I just delete the info.plist entry and load the nib file programmatically in “application: didFinishLaunchingWithOptions:” using a view controller ?

(Now the project has been moved to Xcode 4.2. But I guess the compiler version shouldn’t matter much for this case …)

Hope that somebody knowledgable in this area could help …

Answer 1

If you are upgrading the same project then no you can not just do that.

The mechanism Apple is using in their templates for getting into the app has changed between these versions.

In 3.x the Main Interface is set to MainWindow.xib in your project settings. In this xib your app delegate is loaded as an object.

In 4.x the main.m specifically loads the app delegate with this line:

return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));

it’s the last argument that has changed between 3.x and 4.x

Your best bet is to create a new project and see how the template code has it all wired up.

UPDATE

First off if your project is working do you really need to change it?

If so then I’m using the template code from a fresh project

Go to your main.m and change the implementation from

int main(int argc, char *argv[]) 
{
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
    int retVal = UIApplicationMain(argc, argv, nil, nil);
    [pool release];
    return retVal;
}

to

int main(int argc, char *argv[])
{
    @autoreleasepool {
        return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
    }
}

NB Change AppDelegate to the name of your app delegate class.

You will also need to update your app delegate to create the UIWindow programatically.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    // Instantiate your rootViewController

    self.window.rootViewController = yourRootViewController;
    [self.window makeKeyAndVisible];
    return YES;
}

These are the most obvious differences I can think of, there may be some other subtitles but I’ve not used 3.x in so long I can’t remember.