React navigation header hooks example

example1.js

function MyScreen({}) {
  const [numSelected setNumSelected] = useState(false);
  useHeaderTitle(numSelected > 0 ? `${numSelected} tasks selected` : 'Task selection');
  return ...
}

example2.js

function MyScreen({}) {
  const [doApiRequest, isLoading] = useMyApi();
  useHeaderRight(
    isLoading ? <ActivityIndicator /> : 
      <Button onPress={doApiRequest}>Done</Button>
  )
  return ...
}