iPhone Memory Leaks in Apple's Code

Question

I'm running leaks through Instruments on my iPhone app and I'm seeing a lot of leaks that don't appear to be coming from my code.

For example:

NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request  
                                                              delegate:operation];
operation.urlConnection = connection;
[connection release];

Leaks is telling me that the first line is leaking 1008 bytes. That seems to be a pretty standard alloc init with a release. Other leaks that are mentioned are in UIKit and WebKit.

Is it possible that these leaks are in fact in Apple's frameworks, or is more likely my code and leaks isn't showing the information accurately?

Answer 1

It's entirely possible that Apple's frameworks have leaks in them (however unlikely it may seem) - there were several in the Core Data implementation for iPhone in the 3.0 GM release.

What you should do when you suspect such a thing is try to find a sample project from Apple that uses the functionality you're looking at or reduce your own code as much as possible (maybe build a minimal side project), then test that with Instruments. If you can reproduce the leak reliably, submit a bug to Apple.

Answer 2

Besides that, have you tried to test the app on device instead of simulator? Running instruments on simulator is not very accurate and reliable. Try this one as well http://www.tuaw.com/2009/09/08/xcode-3-2-daily-tip-analyzing-your-code/

Answer 3

Do you keep a reference to your delegate object anywhere else?

If you think about it, Leaks would assume delegate is a leak if you have no other references to it around but it is still retained. Also, how are you freeing your delegate (named operation) when the request is done?

Answer 4

Are you running with NSZombieEnabled? That will cause fake "leaks" to show up in Instruments.

Answer 5

I think this is where your leak stems:

operation.urlConnection = connection;

You may not be doing proper memory management in operation.