Trying without success to add Navigation Controller to existing iOS app - ios

Question

I'm experimenting with OAuth 2.0. which brings up a window containing a UIWebView as a canvas for the authentication server to communicate through. Right now, it is being shown as a modal view with its own view controller, and doesn't have a back button or cancel button. So the user has no way to escape from the sign-in process.
I want to have the webView handled by a navigation controller so I can push the webView's view controller.
I am having problems with doing this. It seems to me I should be able to just create a UINavigationController object with the root view controller being the main view controller, like this
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:self];
However, this line crashes the program without any error message in the debugger.
I thought I could place a line to push the web view controller immediately after the line above, like this:
[navController pushViewController:windowController animated:YES];
But, without getting past the first line, I can't begin to work out the details on getting the web view to show and then configure the back button.
UPDATE
Here is some context. This is in a single view application. The following code is in the main view controller, which brings up the sign-in dialog. I would like to replace the last line, where the presentModalViewController is called, with a push of the windowController onto a navController stack. Note the commented code at the end, where the initialization of the navigation controller is located.
- (IBAction)signInClicked:(id)sender {
if (![self isSignedIn]) {
// Sign in
[self runSigninThenInvokeSelector:#selector(updateUI)];
}
[self updateUI];
}
- (void)runSigninThenInvokeSelector:(SEL)signInDoneSel {
NSString *clientID = mClientId;
NSString *clientSecret = mClientSecret;
// Show the OAuth 2 sign-in controller
NSString *scope = [GDataServiceGoogleBlogger authorizationScope];
GTMOAuth2ViewControllerTouch *windowController;
windowController = [[GTMOAuth2ViewControllerTouch controllerWithScope:(NSString *)scope
clientID:(NSString *)clientID
clientSecret:(NSString *)clientSecret
keychainItemName:(NSString *)kKeychainItemName
delegate:(id)self
finishedSelector:#selector(windowController:finishedWithAuth:error:)] retain];
//UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:self]; // This causes a crash when it is not commented out.
[self presentModalViewController:windowController animated:YES];
}
The application delegate didFinishLaunchingWithOptions is set up this way:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
// Override point for customization after application launch.
self.viewController = [[[blogSpotViewController alloc] initWithNibName:#"myNibName" bundle:nil] autorelease];
self.window.rootViewController = self.viewController;
[self.window makeKeyAndVisible];
return YES;
}

Answer 1

Well, you can present this as a modal controller. You just need to arrange to call dismissModalViewController: in response to a button or some other event on the 'windowController'.
But if you want to use a navigation controller, then you can set that up in application:didFinishLaunchingWithOptions: like so:
// create window here like now
blogSpotViewController *viewController = [[blogSpotViewController alloc] initWithNibName:#"myNibName" bundle:nil];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:viewController];
[viewController release];
// TODO: hold onto this navController in a property if you really need that.
self.window.rootViewController = navController;
[navController release];
// present window here as you are now
This embeds your main view controller in a navigation controller. Then back in your runSigninThenInvokeSelector: you can...
[self.navigationController pushViewController:windowController animated:YES];
Hope that points you in the right direction.