You can use exit method to quit an ios app :
exit(0);
You should say same alert message and ask him to quit
Another way is by using [[NSThread mainThread] exit]
However you should not do this way
According to Apple, your app should not terminate on its own. Since the user did not hit the Home button, any return to the Home screen gives the user the impression that your app crashed. This is confusing, non-standard behavior and should be avoided.