Access class variable inside function

Hi guys i want to do this

export class Page {
   isHidden= false;
    public platform: Platform,
    public params: NavParams,
    public viewCtrl: ViewController,
    public toastCtrl: ToastController
  ) {}
  ionViewDidLoad() {
  move() {
    function frame() {
       // some looping logic here, and i want to change is Hidden variable to be true then some component in html can be hidden
       isHidden = true;

But somehow i cant access isHidden , it says undefined, can anybody tell what am i missing ?

Probably how “this” works, which is admittedly very unintuitive.