Yes, when your application is completed, your virtual memory address space of your application will be completely erased / freed. You can fill in -dealloc if you want, but it will never be called, so the only advantage for this is that if you decide to make your object non-single using the track, you have a dealloc method already exists.
It should be borne in mind that any singleton (which will exist throughout the life of your application) that has any cache that can reach a large size should register for UIApplicationDidReceiveMemoryWarningNotification and reduce or reset the cache when necessary, when it appears memory warning.