How to use Loading while loading data from http.get()

Ionic Framework ionic-v3
1

I am loading json data from server, but it’s take some time due to live server, so anyone tell how to use Loading.

let MyOutput = this.dataService.getProducts();
if(MyOutput)
{
MyOutput.map(res => res.json())
.subscribe(
results => {
console.log(results);

        if(results.success)
        {
          this.products = results.products;
        }
        else if(results.message == 'invalid')
        {
          let alert = this.alertCtrl.create({
            title: 'Opps!',
            subTitle: results.description,
            buttons: ['OK']
          });
          alert.present();
        }

      }, error => {
        console.log(JSON.stringify(error.json()));
      },
        () => {
        loading.dismiss();
    });
  }