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FCM Schedule delivery date or time of push notification（2个答案）
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昨天关门了。
这是我的UI

我成功地实现了Firebase通知。当我添加标题、说明和日期并单击该按钮时，会从Firebase向我的设备发送通知。但是，我希望根据我在应用程序中设置的日期和时间接收通知。
通知屏幕截图

我的代码UI代码

DateTime now = new DateTime.now();
  void showDatePickerNextVaccinationDate() {
    DateTime mindate = DateTime(now.year , now.month, now.day);
    DateTime maxdate = DateTime(now.year + 12, now.month, now.day);
    showCupertinoModalPopup(
        context: context,
        builder: (BuildContext builder) {
          return Container(
            height: MediaQuery.of(context).copyWith().size.height * 0.25,
            color: Colors.white,
            child: CupertinoDatePicker(
              maximumYear: now.year + 12,
              minimumYear: now.year ,
              mode: CupertinoDatePickerMode.dateAndTime,
              initialDateTime: mindate,
              onDateTimeChanged: (value) {
                if (value != nextDate) {
                  setState(() {
                    nextDate = value;
                    //calAge();
                  });
                }
              },
              maximumDate: maxdate,
              minimumDate: mindate,
            ),
          );
        });
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextFormField(
              controller: title,
            ),
            TextFormField(
              controller: body,
            ),
            GestureDetector(
              onTap: showDatePickerNextVaccinationDate,
              child: SizedBox(
                width: 500,
                height: 70,
                child: Container(
                  decoration: BoxDecoration(
                    border: Border.all(color: Colors.black),
                    borderRadius: BorderRadius.circular(15),
                  ),
                  child: Row(
                    mainAxisAlignment: MainAxisAlignment.spaceBetween,
                    children: [
                      Padding(
                        padding: EdgeInsets.only(
                          left: 3,
                          top:20,
                          bottom: 10,
                        ),
                        child: Text(
                          nextDate == null
                              ? 'Next Vaccinated Date'
                              : DateFormat('HH MMMM dd yyyy ')
                              .format(nextDate!),
                          style: const TextStyle(
                            fontSize: 16,
                            fontWeight: FontWeight.w300,
                          ),
                        ),
                      ),
                      Icon(
                        Icons.arrow_drop_down,
                        color: Colors.grey[700],
                        size: 30.0,
                      ),
                    ],
                  ),
                ),
              ),
            ),
            GestureDetector(
              onTap: () async {
                String name = "User1";
                String titleText = title.text;
                String bodyText = body.text;
                String selectedNextDate  = nextDate.toString();
                if (name != "") {
                  DocumentSnapshot snap = await FirebaseFirestore.instance
                      .collection("UserTokens")
                      .doc(name)
                      .get();
                  String token = snap['token'];
                  print(token);
                  //call sendPushMessage
                  sendPushMessage(token, titleText, bodyText,selectedNextDate);
                }
              },
              child: Container(
                margin: EdgeInsets.all(20),
                height: 40,
                width: 200,
                decoration: BoxDecoration(
                    color: Colors.red,
                    borderRadius: BorderRadius.circular(20),
                    boxShadow: [
                      BoxShadow(
                        color: Colors.redAccent.withOpacity(0.5),
                      )
                    ]),
                child: Center(
                  child: Text("button"),
                ),
              ),
            )
          ],
        ),
      ),
    );
  }
}

功能

void sendPushMessage(String token, String body, String title,String selectedNextDate) async {
    try {
      await http.post(Uri.parse('https://fcm.googleapis.com/fcm/send'),
          headers: <String, String>{
            'Content-Type': 'application/json',
            'Authorization': 'key=....',
          },
          body: jsonEncode(<String, dynamic>{
            'priority': 'high',

            //want this to when click message open that page (payload function)
            'data': <String, dynamic>{
              'click_action': 'Test_Notification',
              'status': 'done',
              'body': '$body $selectedNextDate',
              'title': title,
              "isScheduled" : "true",
              "scheduledTime" : "2023-05-17 18:44:00"

            },
            "notification": <String, dynamic>{
              "title": title,
              "body":'$body $selectedNextDate',
              "android_channel_id": "dbfood",
          "isScheduled" : "true",
          "scheduledTime" : "2023-05-17 18:44:00"
            },
            "to": token,
          }));
    } catch (e) {
      if (kDebugMode) {
        print("Error push notification");
      }
    }
  }

我怎么解决这个问题？