Question

I have an app that is loading a overlay controller (shows camera so I can scan). It works great on the iPhone and it works great on the iPad after I call it a second time. Let me explain.

I have a UIButtonBarItem that loads a view controller modally. There are several controls on in the controller, most buttons (defined using a nib). If I load the controller (by responding to the UIButtonBarItem action) on an iPhone, it loads and all the buttons work fine, every time.

But… if I load the same view controller using an UIPopoverController, none of the buttons will respond the first time I load it. So, I touch the screen somewhere outside of the controller and dismiss the controller. Then, I touch the same action button again and now when the controller loads, all the controls in the the view controller work great. REALLY WEIRD!

[POSSIBLE HINT]
The buttons were placed all over the place in weird positions when I loaded it the first time. Each subsequent call had the buttons showing in the right places. I got this to work by disabling “Autoresize subviews” in the nib. The buttons are now in the right places but they still won’t respond when I load this popover the first time.

Here’s the code I’m using to respond to the UIButtonBarItem.

 -(void)launchOverlayController:(id)sender
 {
if([pickerControllerPopover isPopoverVisible])
{
    [pickerControllerPopover dismissPopoverAnimated:YES];
    pickerControllerPopover = nil;
    return;
}

// Deselect any selected cell
[self.tableView deselectRowAtIndexPath:self.tableView.indexPathForSelectedRow animated:NO];


// Working code that shows the overlay (camera on) but the overlay takes the whole screen
SRSScanVINViewController *scanVINViewController = [[SRSScanVINViewController alloc] init];
[pickerController setOverlay:scanVINViewController];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:scanVINViewController];
[navController setModalPresentationStyle:UIModalPresentationFormSheet];
[navController setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
[[UIApplication sharedApplication] setStatusBarHidden:YES];
if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad)
{
    pickerControllerPopover = [[UIPopoverController alloc] initWithContentViewController:pickerController];
    [pickerControllerPopover setDelegate:self];
    [pickerControllerPopover setPopoverContentSize:CGSizeMake(320.0f, 460.0f)];
    [pickerControllerPopover presentPopoverFromBarButtonItem:sender permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}
else
{
    [self presentViewController:pickerController animated:YES completion:nil];
}

 }

I’m totally out of ideas. I can’t see why the controls within the overlaycontroller would work fine every time I call it except for the first time.

Thanks for anyones help in advance.

Answer 1

So the answer is that the superclass is mucking with your view. I’m going to guess it was not designed to be subclassed, but no way to know for sure. What it does in one of the ‘view..’ methods is to override self.view with its own view, and make your view a subview of that view. The first time around it makes the frame of your view have zero dimensions. The next time it leaves it as it was before – maybe some persistent flag. It also inserts the view at different places in its subviews, which seems odd but if you have the code you’d probably see why.

Soooo – the solution to the problem is to just move your view’s subviews to the superView (the subclass’s view), then set your view’s frame to the null frame:

- (void) viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];  // StackOverflow says to add this TCL?

    // Set the initial scan orientation
    [self setLayoutOrientation:self.parentPicker.orientation];

    if ([self.parentPicker hasFlash])
    {
        [flashButton setEnabled:YES];
        [flashButton setStyle:UIBarButtonItemStyleBordered];
        [self.parentPicker turnFlash:NO];
    } else
    {
        [flashButton setEnabled:NO];
    }

    textCue.text = @"";
    viewHasAppeared = NO;

    // move the subviews    
    while([self.view.subviews count]) [self.view.superview addSubview:[self.view.subviews objectAtIndex:0]];
    self.view.frame = CGRectMake(0,0,0,0);
}

PS: note that you were missing a superView call here but it didn’t seem to matter much (you don’t know which method your complex superclass may want so I’d be sure to send them everything you intercept.