Enqueue notification when run loop is idle

gistfile1.m

NSNotification *idleNotif = [NSNotification notificationWithName:NotificationCleanUpOnIdle object:nil];
[[NSNotificationQueue defaultQueue] enqueueNotification:idleNotif postingStyle:NSPostWhenIdle];

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(onSystemIdle:) name:NotificationCleanUpOnIdle object:nil];


// ....

- (void) onSystemIdle:(NSNotification*)notification
{
     // Clean up database in a separate thread for example 
}