[Local Storage in Ionic] For storing and retriving the values loacally when no connection

any.service.ts

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { NetworkService, ConnectionStatus } from './network.service';
import { Storage } from '@ionic/storage';
import { Observable, from } from 'rxjs';
import { tap, map } from "rxjs/operators";

const API_STORAGE_KEY = 'specialkey';

export class YoutubeService {

  constructor(private http: HttpClient,
    private networkService: NetworkService,
    private storage: Storage) { }


  getVideos(forceRefresh: boolean = false, playlistId): Observable<any[]> { 
    if (this.networkService.getCurrentNetworkStatus() == ConnectionStatus.Offline || !forceRefresh) {
      return from(this.getLocalData(playlistId));
    } else {
    return this.http.get('')
      .pipe(map((res: Response) => res['items']),
      tap(res => {
        this.setLocalData(playlistId, res);
      }));
    }
  }


  private setLocalData(key, data) {
    this.storage.set(`${API_STORAGE_KEY}-${key}`, data);
  }

  private getLocalData(key) {
    return this.storage.get(`${API_STORAGE_KEY}-${key}`);
  }

}