NSException错误似乎是随机发生的

Question

这段代码工作正常，现在由于某种原因我得到一个NSException错误，它在以下代码行生成一个SIGABRT ...

 self.popoverController = [[[UIPopoverController alloc] initWithContentViewController:wbPopOverController] autorelease];

这是它所在的方法......

-(IBAction)showPop:(id)sender {

//close any open popovers
[self.popoverController dismissPopoverAnimated:NO];

// Initialize wbPopUpViewController
PopoverAircraftClass *wbPopOverController = [[PopoverAircraftClass alloc] initWithNibName:@"PopoverAircraftClass" bundle:[NSBundle mainBundle]];
wbPopOverController.contentSizeForViewInPopover = CGSizeMake(175, 216);
wbPopOverController.delegate = self; //for update    

[wbPopOverController setAircraftList:aircraftList withCurrentValue:activeRegistration];

// Object converted to UIPopOverController (retained so we can reference it)
self.popoverController = [[[UIPopoverController alloc] initWithContentViewController:wbPopOverController] autorelease];
self.popoverController.passthroughViews = [NSArray arrayWithObject: self.view];

[self.popoverController presentPopoverFromRect:[sender frame] inView:self.layoutViewIB permittedArrowDirections:UIPopoverArrowDirectionUp animated:NO];
[wbPopOverController release];
}

我可能会告诉你，我是新手。关于什么产生NSException的任何想法？