React useState hooks not updating render Text - react-native

Question

I'm using hooks to print a list of conversations, with the name of the contact and the last message for each.
I'm using an interval to check for each conversation if the last message has changed. It's working find with the API, I get the content and use setState to change it, but when I try to get it in the render part, I get the old one.
Here is some code:
const _getMessages = () => {
setDataMsg('');
if (dataContacts) {
dataContacts.map((itemValue, itemIndex) => {
ApiClient.instance.getConversation(itemValue.id).then(response => {
if (response.status === 200) {
setDataMsg([...dataMsg, response.data[response.data.length-1].content]);
console.log('getting all messages ', response.data[response.data.length-1].content);
}
}).catch(error => {
console.log(error);
Alert.alert('Erreur', 'Impossible de récupérer les messages')
})
})
}
else
clearInterval(intervalMsg);
if (props.navigation.state.routeName !== "MessagesPage") {
clearInterval(intervalMsg);
}
}
// Affichage du dernier message //
const _showMessage = (index) => {
if (dataMsg) {
return (dataMsg[index]);
}
return ('Aucun message');
}
And the render:
<FlatList
style={getStyle().messageList}
data={dataContacts}
extraData={dataMsg}
refreshing={true}
keyExtractor={(item) => {
return item.id.toString();
}}
renderItem={({item, index}) => {
return (
<TouchableOpacity
style={getStyle().card}
onPress={() => {
cardClickEventListener(item)
}}>
<View style={getStyle().cardImage}>
<Image style={getStyle().image}
source={_handleImg(item)}/>
</View>
<View style={getStyle().cardContent}>
<Text
style={[getStyle().name, {fontFamily: props.font}]}>{item.firstName + " " + item.lastName}</Text>
<Text
style={{fontFamily: props.font, fontStyle:'italic'}}>{_showMessage(index)}</Text>
</View>
<View style={getStyle().cardIndicator}>
</View>
</TouchableOpacity>
)
}}/>