离子电容器如何获取设备ID

Question

我正在尝试实施推送通知的 Ionic Capacitor 项目。问题是我无法获取设备令牌。我已经按照 Capacitor 网站上提供的文档进行操作，但仍然没有。

我错过了什么？

这是我的服务文件：

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { Plugins, PushNotification, PushNotificationToken, PushNotificationActionPerformed } from '@capacitor/core';
import { AlertButtons, AlertMessage, AlertTypes } from '../interfaces/helper.interface';
import { HelperService } from './helper.service';

import { SERVER_URL } from '../../../environments/environment';

const { PushNotifications } = Plugins;

@Injectable( { providedIn: 'root' } )
export class PushNotificationsService {

    private endPoint = `${SERVER_URL}/device`;

    constructor(
        private helperService: HelperService,
        private httpClient: HttpClient
    ) {}

    public initializeNotificationTasks() {
        this.registerDevice();
        this.requestPermission();
        this.listenToNotifications();
    }

    private requestPermission() {
        console.log('request permission')
        PushNotifications.requestPermission()
            .then(res => {
                console.log(res.granted)
                if (res.granted) {
                    PushNotifications.register();
                } else {
                    this.helperService.displayAlert(AlertTypes.ERROR);
                }
            })
            .catch( (e) => {
                const errorMessage = new AlertMessage();
                errorMessage.title = 'Error';
                errorMessage.message = e;
                errorMessage.buttons = [AlertButtons.DISMISS];
                this.helperService.displayAlert(AlertTypes.ERROR, errorMessage);
            });
    }

    private registerDevice() {
        PushNotifications.addListener( 'registration', ( token: PushNotificationToken ) => {
            return this.httpClient.post(this.endPoint, { device_id: token.value });
        } );
    }

    private listenToNotifications() {
        PushNotifications.addListener('pushNotificationReceived', (notification: PushNotification) => {
            // Returns as JSON.stringfy(notification)
            return notification;
        });
    }
}