data in flatlist vanished after refresh react native code example

Example 1: flatlist onrefresh react native

const [isFetching, setIsFetching] = useState(false);

const fetchData = () => {
  dispatch(getAllDataAction(userParamData));
  setIsFetching(false);
};

const onRefresh = () => {
  setIsFetching(true);
  fetchData();
};

<FlatList
  data={topics}
  keyExtractor={(item) => item.id.toString()}
  renderItem={renderItem}
  onRefresh={onRefresh}
  refreshing={isFetching}
  progressViewOffset={100}
  ListEmptyComponent={<Empty message="No data found." />}
/>;

Example 2: flatlist onrefresh react native

const [isFetching, setIsFetching] = useState(false);

const fetchData = () => {
  dispatch(getAllTopicAction(userParamData));
  setIsFetching(false);
};

const onRefresh = () => {
  setIsFetching(true);
  fetchData();
};

<FlatList
  data={topics}
  keyExtractor={(item) => item.id.toString()}
  renderItem={renderItem}
  onRefresh={onRefresh}
  refreshing={isFetching}
  progressViewOffset={100}
  ListEmptyComponent={<Empty message="No data found." />}
/>;