Question

I want to close my app when an Internet connection is not available.

I check that, but how can I create an alert, and then close my app?

Answer 1

You shouldn’t force close an app as the standard way to terminate an application is to press the home button (or use the multitasking bar)

Don’t Quit Programmatically

---

Never quit an iOS application programmatically because people tend to
interpret this as a crash. However, if external circumstances prevent
your application from functioning as intended, you need to tell your
users about the situation and explain what they can do about it.
Depending on how severe the application malfunction is, you have two
choices.

Display an attractive screen that describes the problem and suggests a
correction. A screen provides feedback that reassures users that
there’s nothing wrong with your application. It puts users in control,
letting them decide whether they want to take corrective action and
continue using your application or press the Home button and open a
different application

If only some of your application’s features are not working, display
either a screen or an alert when people activate the feature. Display
the alert only when people try to access the feature that isn’t
functioning.

^Source