Window Controllers & Window Deallocation
Window Controllers & Window Deallocation
- Subject: Window Controllers & Window Deallocation
- From: Eric Gorr <email@hidden>
- Date: Tue, 18 Jan 2011 14:46:32 -0500
This seems like it should have an easy answer and one that I should know, but my brain has frozen up on this and I cannot seem to determine if things are working as expected or if there is something more I should be doing.
First, here is a sample project that demonstrates the behavior I am seeing:
http://ericgorr.net/cocoadev/trackingarea.zip
Once you build and launch the application, a window will appear with a single button with the label 'Button'. Push the button.
After pushing the button, another window will appear. This is a modal window run using NSApplication's runModalForWindow. It is also owned by the WindowController class.
The second window has a single button on it with the label 'Quit'. Push the button.
This will call NSApplication's stopModal method and everything will be deallocated.
So, what's the problem you might be wondering? Well, it is the order of deallocation and the unexpected delay in deallocating the window.
What you will see if you put a breakpoint in the dealloc method of the window is that the window is deallocated long after the pushed: method in trackingareaAppDelegate has finished and the WindowController has gone away.
Now, in the case of the real application, the window has a view which has a tracking area and the tracking area wants to call a method in the WindowController. For some reason, the after the controller was deallocated, but before the window is deallocated, the tracking area calls into the window controller one last time and the application crashes. (My sample app won't crash)
So, what I am wondering is why my window is staying around...? I would have thought that after the window controller was deallocated, that the window would be as well. Is there a way to force the window to be deallocated before the controller is deallocated?
The only solution I can come up with is that the window controller needs to make sure the tracking area has been removed before it is fully deallocated. Is this what I should be doing? Should the WindowController's dealloc method be written as:
- (void) dealloc
{
[aView removeTrackingArea:myArea];
[aView release];
[super dealloc];
NSLog( @"WindowController Dealloc" );
}
While my sample project isn't crashing, I figure that is only because I am getting lucky and the tracking area is not firing one last time after the controller has gone away.
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