授予权限后无法获取用户位置

Question

我尝试使用 Flutter location 包单击按钮时获取用户位置

代码

FloatingActionButton(
  onPressed: () async {
    await location
        .hasPermission()
        .then((PermissionStatus status) async {
      if (_permissionGranted == PermissionStatus.denied) {
        await location.requestPermission().then(
          (PermissionStatus requestStatus) async {
            print("PERMISSION TAKEN");
            await location
                .getLocation()
                .then((LocationData userLocation) {
              print("LOCATION TAKEN 1");
              print(userLocation);
            });
          },
        );
      } else {
        await location
            .getLocation()
            .then((LocationData userLocation) {
          print("LOCATION TAKEN 2");
          print(userLocation);
        });
      }
    });
  },
  child: Icon(Icons.place, color: Colors.white),
  backgroundColor: Colors.green,
),

当用户单击按钮请求位置权限时，在我的代码中授予权限后工作我的代码的这部分

print("PERMISSION TAKEN");

但是这部分代码不能工作

await location
    .getLocation()
    .then((LocationData userLocation) {
  print("LOCATION TAKEN 1");
  print(userLocation);
});

Answer 1

我得到当前位置如下，尝试像这样使用

Future<LatLng> getUserLocation() async {
 LocationData currentLocation;

var location = new Location();
bool _serviceEnabled;
PermissionStatus _permissionGranted;
LocationData _locationData;

_serviceEnabled = await location.serviceEnabled();
if (!_serviceEnabled) {
  _serviceEnabled = await location.requestService();
  if (!_serviceEnabled) {
  }
}

_permissionGranted = await location.hasPermission();
if (_permissionGranted == PermissionStatus.DENIED) {
  _permissionGranted = await location.requestPermission();
  if (_permissionGranted != PermissionStatus.GRANTED) {
  }
}

  // Platform messages may fail, so we use a try/catch PlatformException.
try {
  currentLocation = await location.getLocation();
  final lat = currentLocation.latitude;
  final lng = currentLocation.longitude;
  final coordinates = new Coordinates(lat, lng);
  var addresses =
      await Geocoder.local.findAddressesFromCoordinates(coordinates);

  var first = addresses.first;
  updateLocation(lat, lng, first.postalCode, first.locality,
      first.countryName, first.adminArea, first.addressLine);

  final center = LatLng(lat, lng);

  return center;
} on PlatformException catch (e) {
  if (e.code == 'PERMISSION_DENIED') {
    showToast("LOCATION PERMISSION DENIED",
        gravity: Toast.TOP, duration: Toast.LENGTH_LONG);
  }
  currentLocation = null;
}
}

别忘了在 Info.plist 中添加这个权限

NSLocationWhenInUseUsageDescription
NSLocationAlwaysUsageDescription

Answer 2

您也可以通过以下方式获取位置：---------

依赖项下的pubspec.yaml文件：----

dependencies:
 location: ^3.0.0

Android，在 AndroidManifest.xml 中添加此权限：

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

iOS，你必须在 Info.plist 中添加这个权限：

NSLocationWhenInUseUsageDescription
NSLocationAlwaysUsageDescription

警告：目前 iOS 模拟器中存在一个错误，您必须手动选择多个位置才能让模拟器实际发送数据。在 iOS 模拟器中测试时请牢记这一点。

main.dart

import 'package:flutter/material.dart';
import 'package:location/location.dart';

void main() => runApp(MyApp());

 class MyApp extends StatelessWidget {
 // This widget is the root of your application.
 @override
Widget build(BuildContext context) {
return MaterialApp(
  title: 'Flutter GPS',
  theme: ThemeData(
    primarySwatch: Colors.blue,
  ),
  home: GetLocationPage(),
);
}
}

class GetLocationPage extends StatefulWidget {
 @override
_GetLocationPageState createState() => _GetLocationPageState();
}

 class _GetLocationPageState extends State<GetLocationPage> {
  LocationData _currentLocation;
  Location _locationService = new Location();

  @override
  void initState() {
// TODO: implement initState
super.initState();

_getLocation().then((value) {
  setState(() {
    _currentLocation = value;
  });
});
 }

    @override
   Widget build(BuildContext context) {
   return Scaffold(
  appBar: AppBar(),
  body: Center(
    child: Column(
      mainAxisAlignment: MainAxisAlignment.center,
      children: <Widget>[
        _currentLocation == null
            ? CircularProgressIndicator()
            : Text("Location:" +
                _currentLocation.latitude.toString() +
                " " +
                _currentLocation.longitude.toString()),
     

      ],
    ),
  ),
);
 }

  Future<LocationData> _getLocation() async {
   LocationData currentLocation;
try {
  currentLocation = await _locationService.getLocation();
} catch (e) {
  currentLocation = null;
}
return currentLocation;
 }
}

ss:---

为了请求位置，您应该始终手动检查位置服务状态和权限状态。参考这个https://pub.dev/packages/location