app.component.ts

  setupOneSignal(){
    this.oneSignal.startInit('ab4692d4...');

    this.oneSignal.inFocusDisplaying(this.oneSignal.OSInFocusDisplayOption.Notification);

    this.oneSignal.handleNotificationReceived().subscribe((jsonData) => {
      if (jsonData.isAppInFocus){
        let alert = this.alertCtrl.create({
           title: notification.title,
           message: notification.body,
           buttons: ['OK']
         });

         alert.present();
      }
    });

    this.oneSignal.iOSSettings({kOSSettingsKeyAutoPrompt: false, kOSSettingsKeyInAppLaunchURL: false});

    this.oneSignal.endInit();

    this.oneSignal.getIds().then((deviceID) => {
      let _vendor = this.platform.is('android') ? 'android' : 'ios';
      let deviceData = {player_id: deviceID.userId, token: deviceID.pushToken, vendor: _vendor}
      this.sessionProvider.saveDeviceData(deviceData);
    });
}