Lost connection to device. Exited (sigterm) - Flutter Crash - ios

Question

My Flutter app is crashing on loading
It operates a FutureBuilder and I believe this to be where the issue comes from.
My app makes an API Call and returns the data to a map marker.
When i have the FutureBuilder return a list view it works fine.
However, when i change it to return a Stack containing my Map SDK and the buttons to call the API it crashes on start up.
Relevant code is below, thank you!
class HomePage extends StatefulWidget {
#override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
Future<Stations> stations;
BuildContext _context;
MapMarkerExample _mapMarkerExample;
#override
void initState() {
stations = API_Call().fetchStations();
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Example 1'),
),
body: Container(
child: FutureBuilder<Stations>(
future: stations,
builder: (context, snapshot) {
if (snapshot.hasError) {
return Text("Error");
}
if (snapshot.connectionState == ConnectionState.done) {
return
Stack(
children: [
HereMap(onMapCreated: _onMapCreated),
Column(
mainAxisAlignment: MainAxisAlignment.start,
children: [
Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
button('Stations Near Me', _anchoredMapMarkersButtonClicked),
button('Clear', _clearButtonClicked),
],
),
],
),
],
);
}
return Text("Loading");
}
)
)
);
}
api_call.dart
class API_Call {
Future<Stations> fetchStations() async {
var client = http.Client();
final response = await client.get(
'https://transit.hereapi.com/v8/stations?in=x,-x&return=transport&apiKey=API_KEY');
if (response.statusCode == 200) {
return Stations.fromJson(jsonDecode(response.body));
} else {
throw Exception('Failed to load stations');
}
}
}
api_manager.dart
typedef ShowDialogFunction = void Function(String title, String message);
class MapMarkerExample{
void showAnchoredMapMarkers() {
print('step5');
GeoCoordinates geoCoordinates = _callGeoCoordinates();
// use the coords .. to add a marker
_addCircleMapMarker(geoCoordinates, 0);
_addPOIMapMarker(geoCoordinates, 1);
print('step6');
}
GeoCoordinates _callGeoCoordinates() {
print('step7');
var stations;
Future<Stations> fetchStations() async {
stations = await API_Call().fetchStations();
for (Station stations in stations) {
GeoCoordinates geoCoordinates = GeoCoordinates (stations.place.location.lat, stations.place.location.lng);
// use the coords .. to add a marker
_addCircleMapMarker(geoCoordinates, 0);
_addPOIMapMarker(geoCoordinates, 1);
}
}
}
HereMapController _hereMapController;
List<MapMarker> _mapMarkerList = [];
MapImage _poiMapImage;
MapImage _circleMapImage;
ShowDialogFunction _showDialog;
List<MapMarker3D> _mapMarker3DList = [];
MapMarkerExample(ShowDialogFunction showDialogCallback, HereMapController hereMapController) {
_showDialog = showDialogCallback;
_hereMapController = hereMapController;
double distanceToEarthInMeters = 8000;
_hereMapController.camera.lookAtPointWithDistance(
GeoCoordinates(x, -x), distanceToEarthInMeters);
// Setting a tap handler to pick markers from map.
_setTapGestureHandler();
_showDialog("Note", "Tap markers for more.");
}
void clearMap() {
for (var mapMarker in _mapMarkerList) {
_hereMapController.mapScene.removeMapMarker(mapMarker);
}
_mapMarkerList.clear();
for (var mapMarker3D in _mapMarker3DList) {
_hereMapController.mapScene.removeMapMarker3d(mapMarker3D);
}
_mapMarker3DList.clear();
}
Future<void> _addPOIMapMarker(GeoCoordinates geoCoordinates, int drawOrder) async {
// Reuse existing MapImage for new map markers.
if (_poiMapImage == null) {
Uint8List imagePixelData = await _loadFileAsUint8List('assets/poi.png');
_poiMapImage = MapImage.withPixelDataAndImageFormat(imagePixelData, ImageFormat.png);
}
Anchor2D anchor2D = Anchor2D.withHorizontalAndVertical(0.5, 1);
MapMarker mapMarker = MapMarker.withAnchor(geoCoordinates, _poiMapImage, anchor2D);
mapMarker.drawOrder = drawOrder;
Metadata metadata = new Metadata();
metadata.setString("key_poi", "Next Departures");
mapMarker.metadata = metadata;
_hereMapController.mapScene.addMapMarker(mapMarker);
_mapMarkerList.add(mapMarker);
}
Future<void> _addCircleMapMarker(GeoCoordinates geoCoordinates, int drawOrder) async {
// Reuse existing MapImage for new map markers.
if (_circleMapImage == null) {
Uint8List imagePixelData = await _loadFileAsUint8List('assets/circle.png');
_circleMapImage = MapImage.withPixelDataAndImageFormat(imagePixelData, ImageFormat.png);
}
MapMarker mapMarker = MapMarker(geoCoordinates, _circleMapImage);
mapMarker.drawOrder = drawOrder;
_hereMapController.mapScene.addMapMarker(mapMarker);
_mapMarkerList.add(mapMarker);
}
Future<Uint8List> _loadFileAsUint8List(String assetPathToFile) async {
// The path refers to the assets directory as specified in pubspec.yaml.
ByteData fileData = await rootBundle.load(assetPathToFile);
return Uint8List.view(fileData.buffer);
}
void _setTapGestureHandler() {
_hereMapController.gestures.tapListener = TapListener.fromLambdas(lambda_onTap: (Point2D touchPoint) {
_pickMapMarker(touchPoint);
});
}
void _pickMapMarker(Point2D touchPoint) {
double radiusInPixel = 2;
_hereMapController.pickMapItems(touchPoint, radiusInPixel, (pickMapItemsResult) {
// Note that 3D map markers can't be picked yet. Only marker, polgon and polyline map items are pickable.
List<MapMarker> mapMarkerList = pickMapItemsResult.markers;
if (mapMarkerList.length == 0) {
print("No map markers found.");
return;
}
});
}
}

Answer 1

In api_manager.dart, this looks very suspicous, and you aren't returning anything from this function, it could also explain the error saying future not complete
Future<Stations> fetchStations() async {
stations = await API_Call().fetchStations();
for (Station stations in stations) {
GeoCoordinates geoCoordinates = GeoCoordinates (stations.place.location.lat, stations.place.location.lng);
// use the coords .. to add a marker
_addPOIMapMarker(geoCoordinates, 1);
}
// GeoCoordinates geoCoordinates = stations.coordinates;
// _addPOIMapMarker(geoCoordinates, 1);
}
}
You have to return a Stations object from it, try after your for loop something like return stations;, it could fix your problem, if the error changes, it's also a good start.
Also change your line in future builder to this:
if (snapshot.connectionState == ConnectionState.done && snapshot.hasData)
And for the meantime, remove this _setTapGestureHandler(). The crash is most likely caused by some memory leak, and from the code posted, it could be explained by listeners.