IOS App should not be killed in background state

I am trying to understand, is there any way to develop ReactNative app with following conditions:

1. In this application timer will be run in the background state.
2. This application should not be killable in the background state.

In android background timer is work perfect but in IOS when app is in background state since 30 seconds then app is killed in background state.

I used 'react-native-background-timer' package for timer.

Please help me to run background timer in IOS for more than 30 seconds or some minutes.Thanks.