Missing UITableView after swapping in a UINavigationController

Question

Hi all,

I've been working on a simple iPhone app for a couple of days now, and haven't been able to wrap my head around quite a bit of the interface. Specifically, I've got a main menu view with an ImageView and a couple of buttons that will eventually swap out to other views.

In addition to the main menu, I've got a UIViewController subclass called Browse_Phone (it's a Universal app), and it contains a UITableView called tableView. It'll eventually be hooked up to a database, but for now, the contents of the table are hard-coded. The following is the table delegate code in Browse_Phone.m (most of this code is borrowed from online examples):

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return 5;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier] autorelease];
    }

    NSString *szCell = [[NSString alloc] initWithFormat: @"Row %i", indexPath.row ];

    cell.textLabel.text = szCell;

    [szCell release];

    // Set up the cell
    return cell;
}

// The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])
    {
        self.title = @"Browse";
        tableView = [[UITableView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        tableView.delegate = self;
        tableView.dataSource = self;
        self.view = tableView;
    }
    return self;
}

Finally, in the main window, there's a button to swap out the main menu view with a navigation controller that uses a Browse_Phone controller as its RootViewController (note that [sender superview] is the main menu view):

- (IBAction)loadBrowse:(id)sender
{
    Browse_Phone *browsePhone = [[[Browse_Phone alloc] initWithNibName:nil bundle:nil] autorelease];
    if(browsePhone.view)
    {
        UINavigationController *navController = [[[UINavigationController alloc] initWithRootViewController:browsePhone] autorelease];
        CGContextRef context = UIGraphicsGetCurrentContext();
        [UIView beginAnimations:nil context:context];
        [UIView setAnimationCurve:UIViewAnimationCurveEaseInOut];
        [UIView setAnimationDuration:0.5];
        [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:window cache:YES];

        [[sender superview] removeFromSuperview];
        [window addSubview:navController.view];

        [UIView commitAnimations];
    }
}

When I press the button, the view swap seems to work. The flip occurs as expected, and the navigation control is loaded, but the table is nowhere to be found. I know the Browse_Phone controller is being instantiated, because the navigation bar's title reflects that of the table. When I used this code in a simple app that just loaded the controllers in the app delegate's didFinishLaunchingWithOptions, it worked just fine. Of course, I know the problem is going to be something simple that I've missed.

Thanks in Advance,

Ryan

Answer 1

It's your initWithNibName:bundle: method.

loadView gets called after initWithNibName:bundle: and overrides your view. You should load your view in loadView, or better yet, subclass UITableViewController (instead of UIViewController) and let it do everything for you.

Answer 2

All right, I think I understand the problem; it looks like somewhere during the creation and initialization of the view controllers, they're being set to autorelease, so when I explicitly set them to autorelease, they wind up being released one too many times. So before the table gets a chance to render, the controller's retain count drops to 0 and it gets dumped. Removing the autorelease from each controller's initialization in loadBrowse fixes the problem. I can't say I understand why the app doesn't just crash outright, but the problem appears to be solved for the time being.