Flutter - Map blank in device Android

Question

I'm trying to show a map in my app made with flutter, I'm using this Widget: flutter_map.

When I test my app in emulator, all works fine:

But when I generate an apk (using command: flutter build apk) to test in my device android, The map is not showing:

My main.dart:

import 'package:flutter/material.dart';
import 'package:flutter_map/flutter_map.dart';
import 'package:latlong/latlong.dart';
 
void main() => runApp(new MyApp());
 
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new MyHomePage(),
    );
  }
}
 
class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => new _MyHomePageState();
}
 
class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
        appBar: new AppBar(title: new Text('Leaflet Maps')),
        body: new FlutterMap(
            options: new MapOptions(
                center: new LatLng(40.71, -74.00), minZoom: 10.0),
            layers: [
              new TileLayerOptions(
                  urlTemplate:"https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png",
                  subdomains: ['a', 'b', 'c']),
              new MarkerLayerOptions(markers: [
                new Marker(
                    width: 45.0,
                    height: 45.0,
                    point: new LatLng(40.73, -74.00),
                    builder: (context) => new Container(
                          child: IconButton(
                            icon: Icon(Icons.location_on),
                            color: Colors.red,
                            iconSize: 45.0,
                            onPressed: () {
                              print('Marker tapped');
                            },
                          ),
                        ))
              ])
            ]));
  }
}

My pubspec.yaml:

name: mapas
description: A new Flutter project.

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.1.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  flutter_map: 0.8.2

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

Pd1: I'm not using Google Maps, I Use OpenStreetMap.

Pd2: I test the apk in several devices Android, always the map is blank.

Any suggestions ??

Answer 1

Most likely you forgot to add <uses-permission android:name="android.permission.INTERNET"/> in the AndroidManifest.xml file.