Cocoa program exits with no crash

I managed to create a bug where a cocoa program is exiting.

-[NSApplication terminate:] is apparently not called.

Nor is -[NSException init].

There is no crash. What I am seeing in gdb is that exit() is being called directly from NSApplicationMain without going through the normal [NSApplication terminate] path.

Any ideas about how to debug this and/or how this (seemingly "impossible" behavior) could happen?

Thanks in adva开发者_如何学运维nce from a cocoa newb.

I would start with judicious use of breakpoints. Narrow it down to the last place where your code is seen before the faux crash and then start looking around that area for memory issues. Whenever I have really strange behavior, it's almost entirely due to a strange memory bug.

There are few remaining routes that would cause your application to voluntarily exit without going through the normal [NSApplication terminate] path.

Try setting a breakpoint on "stop:". I suspect somehow, perhaps an inappropriately named performSelector call? Or a badly named IB connection, you are calling this method, which is documented to exit from the main event loop.

After mulling this over I guessed that I was doing something wrong "in the big picture". So, "in the big picture", what I was doing is calling a modal dialog (by loading a window nib, showing the window and then using [NSApplication beginModalSessionForWindow]...[NSApp runModalSession]... and upon close [NSApp endModalSession]. This has worked for me in other chunks of code no big deal. The critical difference was that this modal window was being loaded and run out of another class's awakeFromNib.

I wrote a simple app that will reproduce this behavior. So what happens is that the modal dialog loads happily and when you close the modal window not only does it close but the app exits. I imagine that this is an "as designed" behavior. I was reading up in apple docs to see if I could understand why this was so but I am will muddled on it. I surmise that somehow my dialog's modal event loop has hijacked the app's event loop so that when the dialog ends so does the app.

If anybody has a better understanding of this mistake please feel free to enlighten us...

Thanks to all for reading and suggestions.

PS -- I changed my code to use [NSApplication runModalForWindow:] instead of the modal session calls and all is well (I think). (Using the modal session would allow me to launch a web browser from a modal dialog -- while runModalForWindow does not -- but in this case I don't need that functionality.)