Question

I’m trying to implement the Paparazzi 2 assignment from the Stanford CS193 course and I’m running into a problem. My one call to save the database is when the app exits (I’m borrowing heavily from Mike Postel’s version to check my code):

- (void)applicationWillTerminate:(UIApplication *)application {
    if (flickrContext != nil) {
        if ([flickrContext hasChanges] == YES) {
            NSError *error = nil;
            BOOL isSaved = [flickrContext save:&error];
            NSLog(@"isSaved? %@", (isSaved ? @"YES" :@"NO") );

            // Replace this implementation with code to handle the error appropriately.
            if(isSaved == NO){
                NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
                abort();
            }
        } 
    }
}

Unfortunately, this doesn’t seem to be doing the job. I’m getting the occasional EXEC_BAD_ACCESS call that might be related to this, but the database never saves. I’ve inserted the save into other pieces and it works fine there, just not in this routine. I’m not releasing any of the managed objects in my views, just the managed object context (flickrContext, or whatever I’m calling it in a view).

Any ideas?

Answer 1

Are you sure that applicationWillTerminate: is even being called?

With iOS4 and background process support, the usual application lifecycle is now:

running -> background -> background suspended -> exit

You get an applicationDidEnterBackground: call when transitioning into the background state, but no further notification when the background process suspends or exits.

So, you really need to save state in applicationDidEnterBackground: for iOS4, as well as in applicationWillTerminate: for older versions