How to save data before app terminates

I know that using beginBackgroundTaskWithName:(Background Execution) my app can have more time to finish its task in background.

But most users have have habit to terminate the app by double clicking the iOS device home button and swipe up to terminate the app.

I have to save around 500 row in DB to prevent user from loosing the data in this situation.

I know using transaction will increase the speed of DB operations.

Question How to guarantee that all data will be saved in this situation and data will not be lost or corrupt, because its very important to save the data.