iPhone SDK: Can't specify view to Navigation Controller

Question

Hi everyone,

I am working on my first iPhone app and making good progress. But there is one thing I just don't understand.

When my app starts it displays a UIView with some functionality on it. This works fine. One of the buttons on that screen is supposed to load a new view (HistoryViewController) which contains a navigation controller.

The problem is… whenever HistoryViewController is loaded the app crashes because there is no view. It's true because in the xib-File I can't connect the File's Owner's view to anything: http://www.freeimagehosting.net/image.php?1a3caa8b8d.png

I definitely have a lack of knowledge somewhere but after hours of research I have not been able to solve this problem.

Any hints? Thank you!

Answer 1

Normally you would either:

• click on that bottom line (History Table View Controller, "HTVC") and in the inspector window specify a NIB Name - which means you would first have to make a new NIB.

or

• doubleclick that bottom line (HTVC), so the 320x480 preview window pops up, and then drag in a UIView from the library.

Using the first method, you tell the view controller to dynamically load the NIB as the view to connect, and using the second method you do this for the view controller using IB. The view you drag in will then show up as a child of that bottom line (HTVC).

edit to actually load the nib file you created, do this to push the view controller:

    UIViewController *controller = [[UIViewController alloc] autorelease];
    [controller initWithNibName:@"nibfilename" bundle:nil];
    [self.navigationController pushViewController:controller animated:YES];

substituting UIViewController for your own view controller class (if needed) and nibfilename with the filename of the nib (minus the extension!)

Answer 2

It's hard to tell what your problem is exactly, but I'll offer some advice.

When creating a navigation controller (or tab controller for that matter) in interface builder, its easy to not understand what is really happening, so my suggestion drop interface builder for a second and lets build it in code.

In general I really dislike building either UI Navigation Controller or tab view controller in interface builder, I really just rather build the views themselves and create the UINavigationController in code.

You have a view which shows the HistoryTableViewController which you want to be contained in a UINavigationController so the code to do this is:

- (void) showHistory 
{
      HistoryViewController *historyVC = [[HistoryViewController alloc] init];
      // If you create historyviewcontroller in nib
      // HistoryViewController *histroyVC [[HistoryViewController alloc] initWithNibName:@"myNib" bundle:nil];

      UINavigationController *navController = [[UINavigationController alloc] initWithRootController:histroyViewController];
      [self presentModalViewContoller:navController animated:YES];
}

This will create a nav controller showing your history view controller as the root view controller. Can't be easier.