Get data from API and using storage of Ionic

I create a news application by getting data from my JSON API and I would simply like to store my data in Ionic's storage and display what's in storage when the user no longer has an internet connection.

Currently, I retrieve my data with the HttpClient and return an Observable .

I can store them in the storage and display it. But I'm not sure that my life cycle is working properly and I don't know if what I did is good.

ArticleService :

import {Injectable} from '@angular/core';
import {HttpClient} from '@angular/common/http';
import 'rxjs/add/operator/map';
import {Platform} from "ionic-angular";
import {ArticleCard} from "../classes/ArticleCard";
import {Observable} from "rxjs/Observable";
import 'rxjs/add/operator/catch';
import 'rxjs/add/operator/map';
import {IArticleCard} from "../interfaces/IArticleCard";

@Injectable()
export class ArticlesService {

  urlArticlesCards: string = "https://mylink";

  constructor(private http: HttpClient, public platform: Platform) {

  }

  getAlaUneCards(): Observable<IArticleCard[]> {
    return this.http.get<any>(this.urlArticlesCards)
      .map(res => {
        return res.map(article => {
          return new ArticleCard(
            article.id,
            article.image,
            article.titre,
          );
        });
      });
  }
}

Interface :

export interface IArticleCard {
  results: {
    id: number;
    image: string;
    titre: string;
  }[]
}

ArticleCard :

export class ArticleCard {
  id: number;
  image: string;
  titre: string;

  constructor(id: number, image: string, titre: string) {
    this.id = id;
    this.image = image;
    this.titre = titre;
  }
}

Home :

  observable$: Observable<IArticleCard[]>;
  tabCards: Array<Object>= [];

  constructor(public navCtrl: NavController, private articleService: ArticlesService, private storage: Storage) {}

  ionViewWillEnter() {

    this.observable$ = this.articleService.getAlaUneCards();

    this.observable$.subscribe(cards => {

      if(cards){
        this.storage.set('alaune_cards', cards);
      }

      this.storage.get('alaune_cards').then((card) => {
        this.tabCards = card;
      })

    });

  }