我遇到的问题是使用世博推送通知API发送推送通知。我正在向Expo推送通知V2 API发送HTTP POST请求，向Expo推送令牌发送通知，该令牌是设备在Expo注册获得的。问题是通知只出现在前台而不是后台。但是，我使用Postman和expo推送通知工具测试发送通知时，它们会出现在后台。
我已经检查了在后台处理通知所需的权限和代码是否到位，并且设备设置是否允许在后台处理通知。我还仔细检查了我的应用程序中Expo推送通知API的实现，以确保我向Expo服务器发送了正确的数据，并且正确地处理了响应。此外，我关闭了电池保护程序，也尝试了其他手机，但都是徒劳的，我还建立了一个独立的apk，但同样的问题与那一个也。
我已经遵循此指南https://docs.expo.dev/push-notifications/push-notifications-setup/
我正在寻求帮助，以了解为什么从我的Expo应用程序发送通知时没有出现在后台，但当我使用Postman和Expo推送通知工具测试它们时会出现。我将感谢任何关于如何解决此问题的指导或建议。

这是我的App.js代码：

async function registerForPushNotificationsAsync() {
    let token;
    if (Device.isDevice) {
        const { status: existingStatus } =
            await Notifications.getPermissionsAsync();
        let finalStatus = existingStatus;
        if (existingStatus !== "granted") {
            const { status } = await Notifications.requestPermissionsAsync();
            finalStatus = status;
        }
        if (finalStatus !== "granted") {
            alert("Failed to get push token for push notification!");
            return;
        }
        token = (await Notifications.getExpoPushTokenAsync()).data;
    } else {
        alert("Must use physical device for Push Notifications");
    }

    if (Platform.OS === "android") {
        Notifications.setNotificationChannelAsync("default", {
            name: "default",
            importance: Notifications.AndroidImportance.MAX,
            vibrationPattern: [0, 250, 250, 250],
            lightColor: "#FF231F7C",
        });
    }

    return token;
}

async function sendPushNotification(
    expoPushToken: any,
    type?: string,
    name?: string
) {

    const message = {
        to: expoPushToken,
        sound: "default",
        title: "HI",
        body: "BY",
    };

    await fetch("https://exp.host/--/api/v2/push/send", {
        method: "POST",
        headers: {
            Accept: "application/json",
            "Accept-encoding": "gzip, deflate",
            "Content-Type": "application/json",
        },
        body: JSON.stringify(message),
    });
}

export default function App() {
    const { isLoadingComplete, user, error, refresh } = useCachedResources();
    const [notifications, setNotifications] = useState<Notification[]>([]);
    const [expoPushToken, setExpoPushToken] = useState<any>();
    const [notification, setNotification] = useState<any>(false);
    const notificationListener = useRef<any>();
    const responseListener = useRef<any>();

    useEffect(() => {
        registerForPushNotificationsAsync().then((token) =>
            setExpoPushToken(token)
        );
        console.log("eee", expoPushToken);
        notificationListener.current =
            Notifications.addNotificationReceivedListener((notification) => {
                setNotification(notification);
            });

        responseListener.current =
            Notifications.addNotificationResponseReceivedListener(
                async (response) => {
                    await Notifications.setBadgeCountAsync(0);
                    navRef.navigate("Dashboard", {
                        screen: "Messages",
                    });
                }
            );

        return () => {
            Notifications.removeNotificationSubscription(
                notificationListener.current
            );
            Notifications.removeNotificationSubscription(responseListener.current);
        };
    }, []);

    useEffect(() => {
        const newNotifications = notifications?.filter(
            (not) => not.status === "new"
        );

        newNotifications?.forEach(async (not) => {
            await sendPushNotification(expoPushToken, not.type, not.by.name);
            updateNotification(not.id!!, {
                status: "old",
            });
        });
    }, [notifications]);

    useEffect(() => {
        // getFCMToken();
        let unsubscribeNotification: Unsubscribe;
        if (user && user.id) {
            unsubscribeNotification = subscribeNotification(
                user.id,
                handleNotificationChange
            );
        }
        return () => {
            if (unsubscribeNotification) {
                unsubscribeNotification();
            }
        };
    }, [user]);

    const handleNotificationChange = (snapshot: QuerySnapshot<Notification>) => {
        let result: Notification[] = [];
        snapshot.forEach((doc) => {
            result.push({ ...doc.data(), id: doc.id });
        });

        setNotifications(result);
    };

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