Multiple modal views tap to dismiss

Question

I set up a mechanism where a modal view controller can be dismissed by tapping the outside of the view. The set up is as follows:

- (void)viewDidAppear:(BOOL)animated
{
    UITapGestureRecognizer *recognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapBehind:)];
    [recognizer setNumberOfTapsRequired:1];
    recognizer.cancelsTouchesInView = NO; //So the user can still interact with controls in the modal view
    [self.view.window addGestureRecognizer:recognizer];

}

- (void)handleTapBehind:(UITapGestureRecognizer *)sender
{
    if (sender.state == UIGestureRecognizerStateEnded)
    {
        CGPoint location = [sender locationInView:nil]; //Passing nil gives us coordinates in the window

        //Then we convert the tap's location into the local view's coordinate system, and test to see if it's in or outside. If outside, dismiss the view.

        if (![self.view pointInside:[self.view convertPoint:location fromView:self.view.window] withEvent:nil]) 
        {
            [self dismissModalViewControllerAnimated:YES];
            NSLog(@"There are %d Gesture Recognizers",[self.view.window gestureRecognizers].count);
            [self.view.window removeGestureRecognizer:sender];
        }
    }
}

This works amazing for dismissing a single modal view. Now suppose I have two modal views, one called from within the root view controller (View A) and then another modal called from within the first modal (View B)

Kind of like this:

Root View -> View A -> View B

When I tap to dismiss View B, all is well. However I get an EXC_BAD_ACCESS error when I try to dismiss View A. After turning on zombies, it seems that View B is still getting the message handleTapBehind: sent to it, even though it's been dismissed and out of memory after View B was closed.

My question is why is View B still being messaged? (handleTapBehind: make sure that gesture recognizer should have been removed from the associated window.) And how can I get it to be sent to View A after View B is already dismissed.

PS. The code above appears both inside the controller for View A and for View B, and it is identical.

EDIT

Here's how I am calling the modal view controller, this code is inside a view controller that is within the standard view hierarchy.

LBModalViewController *vc = [[LBModalViewController alloc] initWithNibName:@"LBModalViewController" bundle:nil];
[vc.myTableView setDataSource:vc];
[vc setDataArray:self.object.membersArray];

[vc setModalPresentationStyle:UIModalPresentationFormSheet];
[vc setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];

[vc.view setClipsToBounds:NO];

[self presentViewController:vc animated:YES completion:nil];

// This is a hack to modify the size of the presented view controller
CGPoint modalOrigin = vc.view.superview.bounds.origin;
[[vc.view superview] setBounds:CGRectMake(modalOrigin.x, modalOrigin.y, 425, 351)];
[vc.view setBounds:CGRectMake(modalOrigin.x, modalOrigin.y, 425, 351)];

That's pretty much it, everything else is pretty standard.

I just pasted your code into a new project with ARC turned on and off and it worked without crashing both ways. Is there anything else that could be referencing View B? — Josh Hudnall
The crash is related to handleTapBehind being sent to an already dismissed view. Nothing else besides the tap gesture has that selector set as the target. My suspicion is I have two tap gestures on top of each other and a single tap triggers them both. I tried to cycle through the array of them and disable all except the one I want to use, but that didn't work. — Andrew Lauer Barinov
That's really strange. What is the full message of the exception? On the surface, it still feels like a delegate variable or something else has a reference to the dismissed view, but obviously you know your code and I don't. If you can think of anything else or want to post more code, I'll be happy to think on it more. — Josh Hudnall
@JoshHudnall thanks for offering to help! I posted some additional code which I use to bring the modal view to the screen. I'll post more stuff if I think of anything else. — Andrew Lauer Barinov

junglecat junglecat · Accepted Answer · 2012-07-14T07:56:34

[self dismissModalViewControllerAnimated:YES];

[self.view.window removeGestureRecognizer:sender];

Should be:

[self.view.window removeGestureRecognizer:sender];

[self dismissModalViewControllerAnimated:YES];

else you will get undefined results.

Multiple modal views tap to dismiss

1 Answers