Why when i close android app, the nativeStorage on ionic not save my data

I have a problem, when I login to the application. Native storage on Ionic keeps the login result data well but when I close my application, the data on nativestorage is gone and also I’m not trigger this.nativeStorage.remove() command. Anyone know what cause this? And how to solve it? i’m using ionic 3

This is the login data when I logged in

   {
    "phonenumber":"12341234",
    "username" : "bingo"
    }

but when I close the application

{
    "phonenumber":"",
    "username":""
    }

the declaration variable

 login : any ={
   phonenumber : '',
   username : '',
  }

the set function

 SetLogin(_login : any)
  {
    this.login.phonenumber = _login.phonenumber;
    this.login.username = _login.username;
    this.nativeStorage.setItem('Loginmodel',this.login );

  }

the get function

 GetLogin()
  { 
    
    this.nativeStorage.getItem('Loginmodel') .then(
      data => {
        console.log(data);
        this.login = data;
      },
      error => console.error(error)
    ); 
    return this.login;
  }

this is when i trigger the function

 googlelogin(){
    this.google.login({})
    .then(res => {
      this.model.id = res.userId;
      this.logincekfbgo('2',res.userId);
    })
    .catch(err => alert('fail')+err);
    
  }
logincekfbgo(lg:any,id:any){
  this.loading.present();
  let headers = new Headers();
  headers.append('Content-Type', 'application/json');
  let data=JSON.stringify({lg:lg,id:id});
  this.http.post(this.pf.getLink('auth'),data,{headers: headers})
  .map(res => res.json())
  .subscribe(res => {
      this.loading.dismissAll();
      if(res.rc =="00")
      {
          this.pf.Popup(res.rcdesc);
          if(res.isregister=="0"){
            this.navCtrl.push(InputnumberPage,{
              id  : this.model.id,
              username:this.model.username,
              email:this.model.email,
              islg:lg,
              tgl : ''
            });
          else{
           this.lgm.SetLogin(res.lgm);
           this.navCtrl.push(MenuTabPage);
          }
         
        }
        else
        {
          this.pf.Popup('fail');
        }
      }
      else
      {
        this.pf.Popup(res.rcdesc);
      }


  }, (err) => {
     this.loading.dismissAll();
      alert("failed");
  });
  this.loading.dismissAll();

}

Please provide the code where you store your data in Native Storage.

i have add it, thanks

When do your functions get triggered?
Maybe the storage gets override with empty values every time you start your app new and after that you try to get the values from the storage, and they are empty then because of that?. Can you profide your complete .ts file?

Also do you test it on Android? If so: Does your Application have the Storage Permission?

i test it on android, i have add the function. thanks