Xamarin Forms - custom map marker not visible - google-maps

I am following article on MS page about Custom map renderer and I can not get it to work for android. Map shows but pins (Markers) are not there. I did not found what I did different from official documents (as in previous link). When I debug, there are 3 markers in customPins collection. And custom renderer works in UWP. So issue is only in Android code.
Here is my CustomRender code for Android which does not shows pins.
using System;
using System.Collections.Generic;
using Android.Content;
using Android.Gms.Maps;
using Android.Gms.Maps.Model;
using Android.Widget;
using iVanApp;
using iVanApp.Android.CustomMapRenderers;
using iVanApp.Droid;
using iVanApp.Model;
using Xamarin.Forms;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Maps.Android;
[assembly: ExportRenderer(typeof(NightMap), typeof(MapRenderers))]
namespace iVanApp.Android.CustomMapRenderers
{
public class MapRenderers : MapRenderer, GoogleMap.IInfoWindowAdapter
{
List<NightPin> customPins;
public MapRenderers(Context context) : base(context)
{
}
protected override void OnElementChanged(Xamarin.Forms.Platform.Android.ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
NativeMap.InfoWindowClick -= OnInfoWindowClick;
}
if (e.NewElement != null)
{
var formsMap = (NightMap)e.NewElement;
customPins = formsMap.NightPins;
}
}
protected override void OnMapReady(GoogleMap map)
{
base.OnMapReady(map);
NativeMap.InfoWindowClick += OnInfoWindowClick;
NativeMap.SetInfoWindowAdapter(this);
}
protected override MarkerOptions CreateMarker(Pin pin)
{
var marker = new MarkerOptions();
marker.SetPosition(new LatLng(pin.Position.Latitude, pin.Position.Longitude));
marker.SetTitle(pin.Label);
marker.SetSnippet(pin.Address);
marker.SetIcon(BitmapDescriptorFactory.FromResource(Resource.Drawable.pin));
return marker;
}
void OnInfoWindowClick(object sender, GoogleMap.InfoWindowClickEventArgs e)
{
var customPin = GetCustomPin(e.Marker);
if (customPin == null)
{
throw new Exception("Custom pin not found");
}
if (!string.IsNullOrWhiteSpace(customPin.Name))
{
}
}
NightPin GetCustomPin(Marker annotation)
{
var position = new Position(annotation.Position.Latitude, annotation.Position.Longitude);
foreach (var pin in customPins)
{
if (pin.Position == position)
{
return pin;
}
}
return null;
}
public global::Android.Views.View GetInfoContents(Marker marker)
{
var inflater = global::Android.App.Application.Context.GetSystemService(Context.LayoutInflaterService) as global::Android.Views.LayoutInflater;
if (inflater != null)
{
global::Android.Views.View view;
var customPin = GetCustomPin(marker);
if (customPin == null)
{
throw new Exception("Custom pin not found");
}
view = inflater.Inflate(Resource.Layout.mtrl_layout_snackbar_include, null);
if (customPin.Name.Equals("Xamarin"))
{
view = inflater.Inflate(Resource.Layout.XamarinMapInfoWindow, null);
}
else
{
view = inflater.Inflate(Resource.Layout.MapInfoWindow, null);
}
var infoTitle = view.FindViewById<TextView>(Resource.Id.InfoWindowTitle);
var infoSubtitle = view.FindViewById<TextView>(Resource.Id.InfoWindowSubtitle);
if (infoTitle != null)
{
infoTitle.Text = marker.Title;
}
if (infoSubtitle != null)
{
infoSubtitle.Text = marker.Snippet;
}
return view;
}
return null;
}
public global::Android.Views.View GetInfoWindow(Marker marker)
{
return null;
}
}
}
DOes anyone have idea why this would not work?
Note: I had to modify official MS code because I got errors. Wherever is Android.Views.View I had to modify it to global::Android.Views.View otherwise I got following error
"'MapRenderers' does not implement interface member
'GoogleMap.IInfoWindowAdapter.GetInfoContents(Marker)'.
'MapRenderers.GetInfoContents(Marker)' cannot implement
'GoogleMap.IInfoWindowAdapter.GetInfoContents(Marker)' because it does
not have the matching return type of 'View'.".
and
The type or namespace name 'Views' does not exist in the namespace
'iVanApp.Android' (are you missing an assembly reference?)
Hope this did not break my code.
After investigating and reading about custom map issues (and mostly solutions) from others I got a workaround solution how to get pins on map but does not show info window when I click on pin(marker). Here I found workaround. If I modify OnMapReday and call&add method SetMapMarkers then pins are visible but as I said no info window is shown when I click on pin
protected override void OnMapReady(GoogleMap map)
{
base.OnMapReady(map);
NativeMap.InfoWindowClick += OnInfoWindowClick;
NativeMap.SetInfoWindowAdapter(this);
SetMapMarkers();
}
private void SetMapMarkers()
{
NativeMap.Clear();
foreach (var pin in customPins)
{
NativeMap.AddMarker(CreateMarker(pin));
}
}
Although this is solution, I would prefer if I could get it to work without this workaround. Hence I did not put much effort why info window is not shown when you click on pin. In case there would be no solution without this workaround then I will be interested in solution with workaround but as I said I do not prefer to go this way.

As FreakyAli said that adding a custom pin and positions for CustomMap.
<local:CustomMap x:Name="customMap" MapType="Street" />
Adding a custom pin and positions the map's view with the MoveToRegion method
public MainPage()
{
InitializeComponent();
var pin = new CustomPin
{
Type = PinType.Place,
Position = new Position(37.79752, -122.40183),
Label = "Xamarin San Francisco Office",
Address = "394 Pacific Ave, San Francisco CA",
Id = "Xamarin",
Url = "http://xamarin.com/about/"
};
customMap.CustomPins = new List<CustomPin> { pin };
customMap.Pins.Add(pin);
customMap.MoveToRegion(MapSpan.FromCenterAndRadius(new Position(37.79752, -122.40183), Distance.FromMiles(1.0)));
}
I can get InfoWindow by clicking map pin, having no problem.

Related

How to make info window of all pin visible by default in Xamarin Form googlemaps

I have rendered google map and pins in the map with googlemaps package in xamarin forms. I want to display title of all pins by default.
I tried
map.SelectedPin = pinname
but it works for only one pin.
Any help will be appreciated
You have to extend the Map class, to create a Bindable list of Pins.
public class BindableMap : Map {
public static readonly BindableProperty MapPinsProperty = BindableProperty.Create(
nameof(Pins),
typeof(ObservableCollection<Pin>),
typeof(BindableMap),
new ObservableCollection<Pin>(),
propertyChanged: (b, o, n) =>
{
var bindable = (BindableMap)b;
bindable.Pins.Clear();
var collection = (ObservableCollection<Pin>)n;
foreach (var item in collection)
bindable.Pins.Add(item);
collection.CollectionChanged += (sender, e) =>
{
Device.BeginInvokeOnMainThread(() =>
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Replace:
case NotifyCollectionChangedAction.Remove:
if (e.OldItems != null)
foreach (var item in e.OldItems)
bindable.Pins.Remove((Pin)item);
if (e.NewItems != null)
foreach (var item in e.NewItems)
bindable.Pins.Add((Pin)item);
break;
case NotifyCollectionChangedAction.Reset:
bindable.Pins.Clear();
break;
}
});
};
});
public IList<Pin> MapPins { get; set; }
}
Then, in your ViewModel
private ObservableCollection<Pin> _pinCollection = new ObservableCollection<Pin>();
public ObservableCollection<Pin> PinCollection { get { return _pinCollection; } set { _pinCollection = value; OnPropertyChanged(); } }
To add a simple pin:
PinCollection.Add(new Pin() { Position = YourPosition, Type = PinType.Generic, Label ="ABCD" });
You can now easily reference this control, with this XAML.
<local:BindableMap MapType="Street" MapPins="{Binding PinCollection}" />

Bad location Google Maps Xamarin Forms (Middle of the ocean)

I'm using Xamarin.forms.Maps and ExtendedMap, I did make a custom control, here I can get the location when the user tap on map but by default the map position is in the middle of the occean, something like this 0.0756931, 0.0786793. I was seaching and trying for a while but I did not find the solution.
I did see that the map is loading the region.LatitudeDegrees and region.LongitudeDegrees but I really don't why is this happen.
Xamarin.Forms 3.0.0.482510
Xamarin.Forms.Maps 3.0.0.482510
Xamarin.Plugin.ExternalMaps 4.0.1
MapGoogleView.xaml
<local:ExtendedMap
WidthRequest="320" HeightRequest="200"
x:Name="MyMap" Tap="OnTap"
IsShowingUser="true"
MapType="Street"/>
MapGoogleView.xaml.cs
public MapGoogleView(double lat, double lon)
{
InitializeComponent();
NavigationPage.SetHasNavigationBar(this, false);
var map = new ExtendedMap(
MapSpan.FromCenterAndRadius(
new Position(lat, lon), Distance.FromMiles(0.3)))
{
IsShowingUser = true,
HeightRequest = 100,
WidthRequest = 900,
VerticalOptions = LayoutOptions.FillAndExpand,
MapType = MapType.Street
};
var stack = new StackLayout { Spacing = 0 };
stack.Children.Add(map);
Content = stack;
var position = new Position(lat, lon); // Latitude, Longitude
var pin = new Pin
{
Type = PinType.Generic,
Position = position,
Label = "UbicaciĆ³n",
Address = "Latitud: " + lat.ToString() + ", Longitud: " + lon.ToString(),
};
MyMap.Pins.Add(pin);
map.MoveToRegion(
MapSpan.FromCenterAndRadius(
new Position(lat, lon), Distance.FromMiles(1)));
}
ExtendedMap.cs
public class ExtendedMap : Map
{
public event EventHandler<TapEventArgs> Tap;
public ExtendedMap()
{
}
public ExtendedMap(MapSpan region) : base(region)
{
}
public void OnTap(Position coordinate)
{
OnTap(new TapEventArgs { Position = coordinate });
}
public async void OnTap(Position coordinate)
{
try
{
OnTap(new TapEventArgs { Position = coordinate });
}
catch (Exception error)
{
await Application.Current.MainPage.DisplayAlert(
"Error",
error.Message,
"Aceptar");
return;
}
}
protected virtual void OnTap(TapEventArgs e)
{
var handler = Tap;
if (handler != null) handler(this, e);
}
}
public class TapEventArgs : EventArgs
{
public Position Position { get; set; }
}
}
Droid
ExtendedMapRenderer.cs
public class ExtendedMapRenderer : MapRenderer, IOnMapReadyCallback
{
private GoogleMap _map;
public void OnMapReady(GoogleMap googleMap)
{
_map = googleMap;
if (_map != null)
//_map.GestureRecognizer.Add(new);
_map.MapClick += googleMap_MapClick;
}
public ExtendedMapRenderer()
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Map> e) //cambiar a xamarin.forms.view
{
if (_map != null)
_map.MapClick -= googleMap_MapClick;
base.OnElementChanged(e);
if (Control != null)
((MapView)Control).GetMapAsync(this);
}
private void googleMap_MapClick(object sender, GoogleMap.MapClickEventArgs e)
{
((ExtendedMap)Element).OnTap(new Position(e.Point.Latitude, e.Point.Longitude));
}
}
If you're struggling to obtain the Latitude and Longitude coordinates using the plugins described above, you could obtain your devices lon/lat by doing the following:
Download and install into your application the Geolocator Plugin. Made by the man the myth the legend James Montemagno.
Following that, you can follow this guide to obtain your devices longitude and latitude coordinates.
On doing that you can assign your global lat and lon variables to the values retrieved using that plugin. I don't know if you did this prior to instantiating your maps or have used a different method but this is how I get my devices Lat & Lon.
As a fallback if a device has location disabled or does not have the ability to retrieve its GPS data I always set my default lat & lon to the capital city of the devices country region.
RegionInfo.CurrentRegion
then if UK set the lat & lon to london city center for example.

Mark Mobile Location on Google Map using Xamarin.Android

Sir,
Developed an application using Xamarin on Visual Studio 2017 where I need to locate the current location of mobile when user turn on Location on his android device and then mark that location on Google Map using MarkerOption. For this I have followed steps as guided in following video https://www.youtube.com/watch?v=rCZN1c2azyE. But didn't got current location on map.
Below is my code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.Gms.Maps;
using Android.Locations;
using Android.Util;
using Android.Gms.Maps.Model;
namespace smvdappdev
{
[Activity(Label = "LOCATION MAP")]
//for google map, for gps location
public class UserLocationMap_Act : Activity, IOnMapReadyCallback, ILocationListener
{
//Map variable
private GoogleMap gooMap;
//Location
LocationManager locManager;
String provider;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Create your application here
SetContentView(Resource.Layout.UserLocationMap);
//Back Button
ActionBar.SetDisplayHomeAsUpEnabled(true);
//Method for Map
SetUpMap();
locManager = (LocationManager)GetSystemService(Context.LocationService);
provider = locManager.GetBestProvider(new Criteria(), false);
Location location = locManager.GetLastKnownLocation(provider);
if (location == null)
{
System.Diagnostics.Debug.WriteLine("No location available!");
}
}
public override bool OnOptionsItemSelected(IMenuItem item)
{
switch (item.ItemId)
{
case Android.Resource.Id.Home:
Finish();
return true;
default:
return base.OnOptionsItemSelected(item);
}
}
//for setting map on fragment placed on activity page
private void SetUpMap()
{
if (gooMap == null)
{
FragmentManager.FindFragmentById<MapFragment>(Resource.Id.fragment1).GetMapAsync(this);
}
}
//to draw map on map display view
public void OnMapReady(GoogleMap googleMap)
{
this.gooMap = googleMap;
//LatLng latlng = new LatLng()
//MarkerOptions mo = new MarkerOptions();
//mo.SetPosition(new LatLng(Convert.ToDouble(32.73), Convert.ToDouble(74.86)));
//mo.SetTitle("Civil Secretarait Jammu");
//googleMap.AddMarker(mo);
googleMap.UiSettings.CompassEnabled = true;
googleMap.UiSettings.ZoomControlsEnabled = true;
googleMap.MoveCamera(CameraUpdateFactory.ZoomIn());
//throw new NotImplementedException();
}
//*** Here all code for getting location via GPS
protected override void OnResume()
{
base.OnResume();
provider = LocationManager.GpsProvider;
//if (locManager.IsProviderEnabled(provider))
//{
locManager.RequestLocationUpdates(provider, 2000, 1, this);
//}
//else
//{
// Log.Info(tag, provider + " is not available. Does the device have location services enabled?");
//}
}
protected override void OnPause()
{
base.OnPause();
locManager.RemoveUpdates(this);
}
public void OnProviderEnabled(string provider)
{
}
public void OnProviderDisabled(string provider)
{
}
public void OnStatusChanged(string provider, Availability status, Bundle extras)
{
}
public void OnLocationChanged(Location location)
{
Double lat, lng;
lat = location.Latitude;
lng = location.Longitude;
MarkerOptions mo = new MarkerOptions();
mo.SetPosition(new LatLng(lat, lng));
//Toast.MakeText(this, "Latitude:" + lat.ToString() + ", Longitude:" + lng.ToString(), ToastLength.Long).Show();
mo.SetTitle("You are here!");
gooMap.AddMarker(mo);
CameraPosition.Builder builder = CameraPosition.InvokeBuilder();
builder.Target(new LatLng(lat, lng));
CameraPosition camPos = builder.Build();
CameraUpdate camUpdate = CameraUpdateFactory.NewCameraPosition(camPos);
gooMap.MoveCamera(camUpdate);
}
}
}
You can just use gooMap.MyLocationEnabled = true. You need to check and request location permission first in order for this to work.
With MyLocationEnabled set to true, it will show a precision circle and a blue dot showing where you are.

Xamarin Forms - Highlight route for WinPhone 8.1 part

Since a long time, I'm trying to make work a polyline for crossplateform using.
I did it and it works well, I followed the Map Control tutorial in first, and then Highlight a Route on a Map tutorial.
I then update the code to make it reloads if a any changes comes, however, I'm getting an issue and I couldn't figure it out... It does works for Android & iOS.
polyline.Path = new Geopath(coordinates); throws Catastrophic failure (Exception from HRESULT: 0x8000FFFF (E_UNEXPECTED))
The problem is that my two others renderer (Android & iOS) works.. Maybe something isn't possible because I work with WinPhone8.1 unlike the tutorial, which is UWP.
public class CustomMapRenderer : MapRenderer
{
MapControl nativeMap;
CustomMap formsMap;
protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
nativeMap = Control as MapControl;
}
if (e.NewElement != null)
{
formsMap = (CustomMap)e.NewElement;
nativeMap = Control as MapControl;
UpdatePolyLine();
}
}
protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (this.Element == null || this.Control == null)
return;
if (e.PropertyName == CustomMap.RouteCoordinatesProperty.PropertyName)
{
UpdatePolyLine();
}
}
private void UpdatePolyLine()
{
if (nativeMap != null)
{
var coordinates = new List<BasicGeoposition>();
foreach (var position in formsMap.RouteCoordinates)
{
coordinates.Add(new BasicGeoposition() { Latitude = position.Latitude, Longitude = position.Longitude });
}
var polyline = new MapPolyline();
polyline.StrokeColor = Color.FromArgb(128, 255, 0, 0);
polyline.StrokeThickness = 5;
polyline.Path = new Geopath(coordinates);
nativeMap.MapElements.Add(polyline);
}
}
}
I also read that a key is needed, so maybe I doesn't use this key in a good way.. I tried with UWP Public Key and WinPhone8.X and earlier Key, but without success too..
Does someone has an idea? This part a really big problem in my app..
Thank in advance !
After a long time, I found why it didn't works...
If you're doing like me, if you do a HttpRequest to something as Google Direction API, then the result will comes after the first passage in the OnElementChanged().
Because formsMap.RouteCoordinates isn't null but empty, the Catastrophic failure (Exception from HRESULT: 0x8000FFFF (E_UNEXPECTED)) is thrown..
This is the good CustomMapRenderer for PolyLine use
using PROJECT;
using PROJECT.UWP;
using System.Collections.Generic;
using Windows.Devices.Geolocation;
using Windows.UI.Xaml.Controls.Maps;
using Xamarin.Forms.Maps;
using Xamarin.Forms.Maps.UWP;
using Xamarin.Forms.Platform.UWP;
[assembly: ExportRenderer(typeof(CustomMap), typeof(CustomMapRenderer))]
namespace PROJECT.UWP
{
public class CustomMapRenderer : MapRenderer
{
MapControl nativeMap;
CustomMap formsMap;
protected override void OnElementChanged(ElementChangedEventArgs<Map> e)
{
base.OnElementChanged(e);
if (e.OldElement != null)
{
nativeMap = Control as MapControl;
}
if (e.NewElement != null)
{
formsMap = (CustomMap)e.NewElement;
nativeMap = Control as MapControl;
UpdatePolyLine();
}
}
protected override void OnElementPropertyChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);
if (this.Element == null || this.Control == null)
return;
if (e.PropertyName == CustomMap.RouteCoordinatesProperty.PropertyName)
{
UpdatePolyLine();
}
}
private void UpdatePolyLine()
{
if (formsMap != null && formsMap.RouteCoordinates.Count > 0)
{
List<BasicGeoposition> coordinates = new List<BasicGeoposition>();
foreach (var position in formsMap.RouteCoordinates)
{
coordinates.Add(new BasicGeoposition() { Latitude = position.Latitude, Longitude = position.Longitude });
}
Geopath path = new Geopath(coordinates);
MapPolyline polyline = new MapPolyline();
polyline.StrokeColor = Windows.UI.Color.FromArgb(128, 255, 0, 0);
polyline.StrokeThickness = 5;
polyline.Path = path;
nativeMap.MapElements.Add(polyline);
}
}
}
}

google map load map using internet or gps

I want to use google map v2 to load the map using either gps or internet, I can do it using just internet.
when I connect my application to internet, the map is loaded successfully, but if i used just gps the map doesn't show even though I have already activiate the gps in my phone and in my app.
this is my code, first i get my location then i load the mapp
setContentView(R.layout.google_map_layout);
locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);
boolean enabled = locationManager
.isProviderEnabled(LocationManager.GPS_PROVIDER);
if (!enabled) {
Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
startActivity(intent);
} else {
Criteria criteria = new Criteria();
provider = locationManager.getBestProvider(criteria, false);
Location location = locationManager.getLastKnownLocation(provider);
if (location != null) {
Toast.makeText(RestaurantsNearBy.this,
location.getLatitude() + "", Toast.LENGTH_LONG).show();
LatLng currentLocation = new LatLng(location.getLatitude(),
location.getLongitude());
new getRestaurantNearBy().execute(currentLocation.latitude,
currentLocation.longitude);
map = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map)).getMap();
map.setInfoWindowAdapter(new InfoWindowAdapter() {
private final View window = getLayoutInflater().inflate(
R.layout.restaurant_marker, null);
#Override
public View getInfoWindow(Marker marker) {
return null;
}
#Override
public View getInfoContents(Marker marker) {
TextView tv_title = ((TextView) window
.findViewById(R.id.tv_title));
TextView tv_description = ((TextView) window
.findViewById(R.id.tv_description));
ImageView iv_image = ((ImageView) window
.findViewById(R.id.iv_image));
AddressMap oneAddres = markersMap.get(marker);
tv_title.setText(oneAddres.getRestaurant().getName());
tv_description.setText(oneAddres.getDescription());
Restaurant r = markersMap.get(marker).getRestaurant();
if (Restaurant.getRestaurant(r.getID()) != null) {
if (Restaurant.getRestaurant(r.getID()).getImage() != null) {
iv_image.setImageBitmap(Restaurant
.getRestaurant(r.getID()).getImage());
} else {
try {
iv_image.setImageBitmap(r
.getImageFromWebService());
} catch (Exception e) {
iv_image.setImageResource(R.drawable.unknown);
}
}
} else {
iv_image.setImageBitmap(r.getImageFromWebService());
}
return window;
}
});
map.setOnInfoWindowClickListener(new OnInfoWindowClickListener() {
#Override
public void onInfoWindowClick(Marker marker) {
final AddressMap oneAddress = markersMap.get(marker);
AlertDialog alertDialog3 = new AlertDialog.Builder(
RestaurantsNearBy.this).create();
alertDialog3.setTitle("Order !");
alertDialog3
.setMessage("Do you want to order from the restaurant "
+ oneAddress.getRestaurant().getName());
alertDialog3.setIcon(R.drawable.more_information);
alertDialog3.setButton("Yes",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog,
int which) {
Basket.setRestaurant(oneAddress
.getRestaurant());
dialog.dismiss();
Intent addAddressIntent = new Intent(
RestaurantsNearBy.this,
OrderMeal.class);
startActivity(addAddressIntent);
}
});
alertDialog3.setButton2("No",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog,
int which) {
dialog.dismiss();
}
});
alertDialog3.show();
}
});
// Move the camera instantly to hamburg with a zoom of 15.
map.moveCamera(CameraUpdateFactory.newLatLngZoom(
currentLocation, 15));
// Zoom in, animating the camera.
map.animateCamera(CameraUpdateFactory.zoomTo(10), 2000, null);
Log.d("Provider ", provider + " has been selected.");
onLocationChanged(location);
} else {
Toast.makeText(RestaurantsNearBy.this, "Sorry we couldn't define your location",
Toast.LENGTH_SHORT).show();
}
}
You should use proper tags, Google Maps can be found on loads of platforms, and you have a question about the android versions, so at least add Android tag.
On the question: Google Maps NEEDS active internet connection, when you first load the maps. V2 does some decent caching on your SD card (sometimes a bit excessive too), allowing you to later check thoose already loaded maps offline, but the principle is: no active internet connection, no Google Maps.
ps: GPS is NOT an internet connection.
By default you can't load the map data properly if you aren't connected with wifi or mobile connection. GPS only lets you find your position.