App crashes on fast exit+restart

I am working with a free app that calculates grades for norwegian high school students. The different subjects are stored in a sqlite database. Everything works fine, except for one thing: If i close the app and restart quickly (faster than, say, one second), it crashes. Also, this only happens if I close the app in specific circumstances involving selecting/checking subjects in a UITableView (the changes are immediately stored in the database). Anyway if I wait for more than one开发者_JAVA技巧 second before restarting the app, it never crashes.

The error is not traced in any way in the console window.

Instruments has found some memory leaks in my app, but they are very small (16 bytes). I presume that is not the reason for the crash (but I will try to stop the leaks). I have also tried deleting and reinstalling the app, and turning the iPod/iPhone on and off. No change...

I understand that I cannot ask anyone to find the error in the extensive code of my app. My questions to you guys are:

1. Have any of you experienced similar errors? Related to sqlite?
2. Do you think App store will reject the app because of this?
3. Does anyone have any idea where to start looking for the error?

I am very thankful for any response!

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When you say "it crashes," what is the actual error you get in the stack on the phone? Is it an actual crash, or are you getting a "failed to launch in time error?"

On iPhone, it's possible for an app's main thread to terminate while still running background nondetached threads. In this sense, despite all the claims that you cannot run in the background, you actually can... for a few seconds. When the main thread terminates, you go back to Springboard, and eventually the OS will kill your process if it doesn't terminate on its own. Do you manage any of your sqlite work on a background thread? Do you create any nondetached threads (this generally requires pthreads, so if you don't know, you probably aren't, but sqlite might; check in Instruments).

It's possible that your last instance still has a lock on your database, and that your re-launch doesn't react well to that lock. Do you have proper error handling around your open?