flutter - 如何在 flutter 中获得经纬度

Question

我可以弄清楚如何将用户的纬度和经度放在一起，但需要单独获取它们以利用 Geolocator 包中的 Geolocator().distanceBetween 函数。我下面的代码不断收到错误:

未处理的异常:NoSuchMethodError:在 null 上调用了 getter 'latitude'。

接收方:空

尝试调用:纬度

  Future<Position> getLocation() async {
    var currentLocation;
    try {
      currentLocation = await geolocator.getCurrentPosition(
          desiredAccuracy: LocationAccuracy.best);
    } catch (e) {
      currentLocation = null;
    }
    return currentLocation;
  }


  void calculateDistance() async {

    getLocation().then((position) {
       userLocation = position;
    });

      final double myPositionLat =  userLocation.latitude;
      final double myPositionLong = userLocation.longitude;

      final double TPLat = 51.5148731;
      final double TPLong = -0.1923663;
      final distanceInMetres = await Geolocator().distanceBetween(myPositionLat, myPositionLong, TPLat, TPLong)/1000;

      print(distanceInMetres);

  }

Answer 1

试试这个 :

void calculateDistance() async {

getLocation().then((position) {
   userLocation = position;


  final double myPositionLat =  userLocation.latitude;
  final double myPositionLong = userLocation.longitude;

  final double TPLat = 51.5148731;
  final double TPLong = -0.1923663;
  final distanceInMetres = await Geolocator().distanceBetween(myPositionLat, myPositionLong, TPLat, TPLong)/1000;

  print(distanceInMetres);

  });
}

或另一种方法是:

void calculateDistance() async {

userLocation = await getLocation();


  final double myPositionLat =  userLocation.latitude;
  final double myPositionLong = userLocation.longitude;

  final double TPLat = 51.5148731;
  final double TPLong = -0.1923663;
  final distanceInMetres = await Geolocator().distanceBetween(myPositionLat, myPositionLong, TPLat, TPLong)/1000;

  print(distanceInMetres);
}