Question

I’m fairly new to Objective-C and iPhone programming so I apologize if this is a newbie question. I have a simple application that needs to go from one view, to another. The first view is a UIViewController. I set up the xib file in IB (i.e. dragged some buttons onto the window) and hooked up all the buttons (which all work). I then created another xib file and class (also a UIViewController) and hooked them up. When a button is pressed in the first view I want to load the second view. Here’s the code that is supposed to be pushing the view:

-(IBAction)createAccount:(id)sender{
    CreateAccountViewController*acctView = [[CreateAccountViewController alloc] initWithNibName:@"CreateAccount" bundle:nil];
    [self.navigationController pushViewController:acctView animated:YES];
    [acctView release];
}

But this does nothing. When I put print statements in the createAccount method those are printed (I can click the button any number of times and it never crashes) but the acctView is never pushed. When I print out the value of self.navigationController it returns null. It’s even stranger because if I present the acctView modally then it works.

-(IBAction)createAccount:(id)sender{
    CreateAccountViewController*acctView = [[CreateAccountViewController alloc] initWithNibName:@"CreateAccount" bundle:nil];
    [self presentModalViewController:acctView animated:YES];
    [acctView release];

}

This works just fine, but I don’t want to use the view modally. I’m completely lost here. In the past couple of hours I’ve come across a lot of posts saying to do something with a UINavigationController and hook that up to my view, but how do I do that? Any help is greatly appreciated! Thanks.

Answer 1

It seems you haven’t created a UINavigationController for your app.

Best thing would be starting from scratch with a new Xcode project, taking care of choosing a Navigation Based application. In this way you will get almost everything already set up for you.

If you don’t like this approach, you can create programmatically your UINavigationController. Here you find a tutorial for doing that.

If you prefer more straight-to-the-point instructions, here they are:

  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    

     MainPageDialog *overviewViewController = [[MainPageDialog alloc] initWithNibName:@"MainPage" bundle:nil];
     self.navigation = [[[UINavigationController alloc] initWithRootController:overviewViewController] autorelease];
     [overviewViewController release];

     [window addSubview:[navigation view]];
     [self.window makeKeyAndVisible];

     return YES;
}

whereby self.navigation is a retained property in your appDelegate.

EDIT:

This answer was quite old, therefore an update:

1. If you are using ARC, you should be using a strong (vs. retain) property and you would not need the autorelease;

2. if you target iOS > 4.0 (which is also implied by the above point), you can use the rootViewController property in UIWindow and say:

    MainPageDialog *overviewViewController = [[MainPageDialog alloc] initWithNibName:@"MainPage" bundle:nil];
    self.window.rootViewController = [[[UINavigationController alloc] initWithRootController:overviewViewController] autorelease];
    [overviewViewController release];
   
    [window addSubview:[self.window.rootViewController view]];
    [self.window makeKeyAndVisible];
   

   without the need for any navigation property.