Appropriate to delete files or close DB connection in dealloc?

I know that dealloc is called when an object's retain count reaches zero and that iVars should be released therein, but I am wondering if it is also an appropriate spot to delete temporary files or close database connections.

Specifically, I have a subclass of UIViewController that creates a database connection in -viewDidLoad and through user interaction, temporary files can be created. I would like to close the DB connection and delete the temporary files (if they exist) when the aforementioned controller gets popped of the navigation stack. Should I do so in dealloc?

My first thought was to do this DB and file clean up in -viewDidUnload, but I now know that this method is only called when a memory warning is issued by the OS. Another thought was to put it in -viewDidDisappear:animated but the issue with that approach is that the another view may go on top of the one controlled by my view controller. In that scenario, I do not want to close the DB connection or clean up the temp files.

If dealloc is not the 开发者_开发百科appropriate spot (this is my gut feeling), where should this type of clean up be done? I would kind of hate to force the parent of my view controller to have to call a method in response to its child getting popped off the navigation stack.

The Apple guide to memory management says, No.

http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/MemoryMgmt/Articles/mmPractical.html#//apple_ref/doc/uid/TP40004447-SW13

In short, don't use dealloc to manage resources.

You can do so in dealloc, or if you need the files around during app lifecycle, on your app delegate's applicationWillTerminate:. YMMV.

Do not try to do this in the dealloc method of your view controller.

What would happen if the view controller gets retained somewhere you're not expecting it? The dealloc method may not get fired, and you clean up never occurs. Maybe that's not the case in the code you're writing now, but something could change in the future.

Is there any specific reason you want to tie the deletion of files and closing of the DB connection to popping off the view controller? If not, perhaps you could do this immediately your query has completed, or it may make sense to open the DB connection on startup/foreground, and then close it on termination/backgrounding.

If you must tie it to view controller being popped off the nav stack, then you could call your clean-up method from viewDidDisappear: