MBProgressHUD causes application to crash

Question

It seems that using MBProgressHUD is causing my application to crash. Without the HUD code, the following runs just fine, but with it, it crashes:

{

    ...

    HUD = [[MBProgressHUD alloc] initWithView:self.view];

    // Add HUD to screen
    [self.view addSubview:HUD];

    // Register for HUD callbacks so we can remove it from the window at the right time
    HUD.delegate = self;

    HUD.labelText = @"Connecting";

    // Show the HUD while the provided method executes in a new thread
    [HUD showWhileExecuting:@selector(runLocalNotificationHandler) onTarget:self withObject:nil animated:YES];  

[[self navigationController] popViewControllerAnimated:YES];
}

- (void) runLocalNotificationHandler
{
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

[self createLocalNotificationWithBug:[self tempBug]];

    [self performSelectorOnMainThread:@selector(finishedUpdatingNotifications) withObject:nil waitUntilDone:NO];

    [pool release];
}

- (void)finishedUpdatingNotifications
{

    [[self navigationController] popViewControllerAnimated:YES];
}

- (void)hudWasHidden {
    // Remove HUD from screen when the HUD was hidden
    [HUD removeFromSuperview];
    [HUD release];
}

The following debug output is produced:

gdb) continue
2010-07-02 00:07:55.224 Bugger[16796:207] >>> Entering -[HomeViewController viewDidAppear:] <<<
2010-07-02 00:07:55.225 Bugger[16796:207] <<< Leaving -[HomeViewController viewDidAppear:] >>>
2010-07-02 00:07:55.224 Bugger[16796:7007] <<< Leaving -[BugDetailViewController runLocalNotificationHandler] >>>
2010-07-02 00:07:55.226 Bugger[16796:207] >>> Entering -[BugDetailViewController prepareToolbar] <<<
2010-07-02 00:07:55.227 Bugger[16796:207] <<< Leaving -[BugDetailViewController prepareToolbar] >>>
2010-07-02 00:07:55.229 Bugger[16796:207] >>> Entering -[BugDetailViewController dealloc] <<<
[Switching to process 16796]
2010-07-02 00:07:55.260 Bugger[16796:207] <<< Leaving -[BugDetailViewController dealloc] >>>
[Switching to process 16796]
Program received signal:  “EXC_BAD_ACCESS”.
(gdb) 

What's going on here?

EDIT: Backtrace:

Program received signal:  “EXC_BAD_ACCESS”.
[Switching to process 23788]
(gdb) bt
#0  0x029b4a93 in objc_msgSend ()
#1  0x00000000 in ?? ()
(gdb) 

Answer 1

So close....

type bt<return> at that (gdb) prompt and post the backtrace.

Beyond that, my best guess is that your delegate -- the self in the above code -- is being released and deallocated without first being removed as delegate from the MBProgressHUD instance. Delegates are typically a weak reference and, thus, that would definitely cause a crash as you describe.

---

Ewwww... your stack has been stomped! I hate it when that happens.

Back to the best guess; is your delegate being deallocated before being removed as the delegate from the MBProgressHUD? ... have you run "Build and Analyze" on your code?