Call variables from method

pushSetup() {
    const options: PushOptions = {
      android: {
        senderID: '111111111111'
      },
      ios: {
        alert: 'true',
        badge: true,
        sound: 'false'
      }
    };

    const pushObject: PushObject = this.push.init(options);
    pushObject.on('registration').subscribe((data: any) => {
      //alert('Device token/handle is: ' + data.registrationId);
          this.regID = data.registrationId;
  });
  }

this registrationId actually any device registrationId.

I want a call the registrationId in

 ngOnInit() {
    console.log('ngOnInit GirisPage');
    this.menuCtrl.swipeEnable(false);
    this.menuCtrl.enable(false);
    this.logForm();
    **this.pushsetup();**
  }

but ı can’t make it. it’s undefined all the time

Can anyone help me. Please