Comment détecter si l'application perd Focus dans React Native

Copyimport { useFocusEffect } from '@react-navigation/native';
function Profile({ userId }) {  const [user, setUser] = React.useState(null);
  useFocusEffect(    React.useCallback(() => {      const unsubscribe = API.subscribe(userId, user => setUser(data));
      return () => unsubscribe();    }, [userId])  );
  return <ProfileContent user={user} />;}
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