Can't make a viewController transparent without EXC_BAD_ACCESS - ios

Question

I'm currently trying to make a small demo app which is supposed to present 2 views at the same time :
- The first one, BaseViewController, is a classic controller with 2 buttons
- The second one, OverViewController, is launch on top of baseView and contains
a last button, and is supposed to be transparent and sending the touch controls
to the first one
Both viewController have their xib. To make it clear : rootView --> baseView + overView (transparent)
My problem is NOT to send the control events from the 2nd view to the first, but to make the 2nd view transparent and functionnal.
Here's what I've tried so far :
1) ------------ Presenting the two view controllers ------------
From the app rootViewController :
- (IBAction)buttonClicked:(id)sender
{
OverViewController *overVC = [[OverViewController alloc] init];
[overVC presentViewControllerFrom:self];
}
From OverViewController :
- (id)init
{
self = [super init];
if (self)
{
self.base = [[BaseViewController alloc] initWithNibName:#"BaseViewController" bundle:nil];
}
return self;
}
I made a custom method to make overView present the baseView before showing up.
- (void)presentViewControllerFrom:(RootViewController *)sender
{
[sender presentViewController:self.base animated:NO completion:nil];
self.view.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.0];
self.view.opaque = NO;
[self.base presentViewController:self animated:YES completion:nil];
}
At this point, the baseView appears, followed by the overView. The button of overView work correctly. Great ! But then the background of overView doesn't show what's supposed to be behind and stays black. No alpha transparency.
2) ------------ Presenting the baseView and adding overView as a subview ------------
From the app rootViewController (same than the one before) :
- (IBAction)buttonClicked:(id)sender
{
OverViewController *overVC = [[OverViewController alloc] init];
[overVC presentViewControllerFrom:self];
}
From OverViewController (not presenting but adding subview) :
- (void)presentViewControllerFrom:(RootViewController *)sender
{
[sender presentViewController:self.base animated:NO completion:nil];
self.view.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.0];
self.view.opaque = NO;
[self.base.view addSubview:self.view];
}
This time, the transparency is great but any touch on the overView button cause a EXC_BAD_ACCESS to show up.
There I am, wondering how to do this. Any help will be greatly appreciated ! :)

Answer 1

Don't use a combination of presenting a view controller and adding subviews. Choose 1. It should be subview that you choose. It can be owned by another controller and that controller should probably be added as a child view controller.
In your first situation you see black because iOS is removing the (now expected to not be visible) view from the view hierarchy. So your view is transparent but what you expect to be behind it is no longer there.
Your second situation is probably just resulting in an invalid view hierarchy somewhere.
The overview controller should not own the base controller. The base controller should be shown and then the overview controller view added as a subview.