Visualise the current state of an application [closed]

1. Which method is called when app is closed?
2. How do I know when my react native app is closed?
3. How do I close the current window in WPF?

Which method is called when app is closed?

The general rule is that either onDestroy() is called, or your process is terminated, or your code crashed.

How do I know when my react native app is closed?

With @react-native-community/hooks you can use the useAppState hook to check the app state. When you close the app, it gets a state of unknown once you open it back. When is in background, it says background' or 'inactive'.

How do I close the current window in WPF?

Pressing ALT + F4 . Pressing the Close button.