Randomly disappearing struct

I've created a Objective-C class to interface with PostgreSQL using libpq. It mostly works but I have one small problem - the connection seems to disappear randomly.

This class is set to open a connection when a window is opened and close that connection before the window closes. On the init code of the window I open the connection and I listen to notifications so I can close the connection with PQfinnish().

Now if I open that window, I can run as many queries as I want. But if I close it and open it again I get an EXC_BAD_ACCESS error. The error seems to be inside libpq but I've no idea what I'm doing wrong - there's no examples to开发者_运维百科 follow which makes it a bit harder to follow patterns.

I believe there seems to be a problem with the connection object but I can't find out exactly what as all diagnostic functions seem to be returning the right values.

Postgresql 8.0, running on latest OS X, latest Xcode and project targeted at 10.5

Found the answer:

The code that crashed was called from an event that was fired from a notification. The crash came because I wasn't unregistering that class from the notification centre when closing the window.

I now unregister that class from the centre and all works well.

No idea why the problem reflected itself on the connection object, though.