Getting stuff to (safely) shut down is another application delegate responsibility. To handle termination, the application delegate implements the delegate method applicationWillTerminate: to save any unsaved data or key application state (where the user is in the application — the current view and stuff like that) to disk. (Okay, I know, the disk in the iPhone is not really a disk; it’s a solid state drive that Apple calls a disk, but if it calls it that, I probably should, too, just so I don’t confuse too many people.). You can also use this method to perform additional cleanup operations, such as deleting temporary files.