PermissionStatus _permissionStatus;

  void _askPermission() {
    PermissionHandler().requestPermissions(
        [PermissionGroup.locationWhenInUse]).then(_onStatusRequested);
  }

  void _onStatusRequested(Map<PermissionGroup, PermissionStatus> statuses) {
    final status = statuses[PermissionGroup.locationWhenInUse];
    if (status != PermissionStatus.granted) {
      PermissionHandler().openAppSettings();
    } else {
      _updateStatus(status);
      Navigator.of(context).pushReplacement(
          new MaterialPageRoute(builder: (context) => new MyAppState()));
    }
  }

  void _updateStatus(PermissionStatus status) {
    if (status != _permissionStatus) {
      setState(() {
        _permissionStatus = status;
      });
    }
  }

  void initState() {
    super.initState();
    PermissionHandler()
        .checkPermissionStatus(PermissionGroup.locationWhenInUse)
        .then(_updateStatus);
  }