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xamarin android webview file upload download does not work . please i am comfortable with c#

i have created a mobile app for my website .the webview does not handle upload and download .so i followed the link Uploading files using a webview in Xamarin Android App and included the code from this link but does not handle upload and download. please guide. the storeactivity.cs code here.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using Android.App;
using Android.Content;
using Android.Net;
using Android.OS;
using Android.Runtime;
using Android.Views;
using Android.Webkit;
using Android.Widget;
namespace smartapp
{
[Activity(Label = "StoreActivity")]
public class StoreActivity : Activity
{
static ProgressBar progressBar;
WebView webview;
IValueCallback mUploadMessage;
private static int FILECHOOSER_RESULTCODE = 1;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.StoresView);
webview = FindViewById<WebView>(Resource.Id.StoreView);
// show progress bar
progressBar = FindViewById<ProgressBar>(Resource.Id.progressBar);
// chrome client to upload files from webview
var chrome = new FileChooserWebChromeClient((uploadMsg, acceptType, capture) => {
mUploadMessage = uploadMsg;
var i = new Intent(Intent.ActionGetContent);
i.AddCategory(Intent.CategoryOpenable);
i.SetType("image/*");
StartActivityForResult(Intent.CreateChooser(i, "File Chooser"), FILECHOOSER_RESULTCODE);
});
webview.LoadUrl("https://smartbook.pk/Stores/index");
webview.SetWebViewClient(new WebViewListener());
// download files from webview
webview.SetDownloadListener(new MyDownloadListerner(this));
webview.SetWebChromeClient(chrome);
webview.Settings.JavaScriptEnabled = true;
}
//
class MyDownloadListerner : Java.Lang.Object, IDownloadListener
{
Context cont;
public MyDownloadListerner(Context context)
{
cont = context;
}
public void OnDownloadStart(string url, string userAgent, string contentDisposition, string mimetype, long contentLength)
{
Android.Net.Uri uri = Android.Net.Uri.Parse(url);
Intent intent = new Intent(Intent.ActionView, uri);
cont.StartActivity(intent);
}
}
//
//
protected override void OnActivityResult(int requestCode, Result resultCode, Intent intent)
{
if (requestCode == FILECHOOSER_RESULTCODE)
{
if (null == mUploadMessage)
return;
Java.Lang.Object result = intent == null || resultCode != Result.Ok
? null
: intent.Data;
mUploadMessage.OnReceiveValue(result);
mUploadMessage = null;
}
}
// file chooser code
partial class FileChooserWebChromeClient : WebChromeClient
{
Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback;
public FileChooserWebChromeClient(Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback)
{
this.callback = callback;
}
//For Android 4.1
[Java.Interop.Export]
public void openFileChooser(IValueCallback uploadMsg, Java.Lang.String acceptType, Java.Lang.String capture)
{
callback(uploadMsg, acceptType, capture);
}
}
// webview listener code here
public class WebViewListener : WebViewClient
{
public override bool ShouldOverrideUrlLoading(WebView view, IWebResourceRequest request)
{
view.LoadUrl(request.Url.ToString());
return true;
}
public override void OnPageStarted(WebView view, string url, Android.Graphics.Bitmap favicon)
{
progressBar.Progress = view.Progress;
}
public override void OnLoadResource(WebView view, string url)
{
progressBar.Progress = view.Progress;
}
public override void OnPageFinished(WebView view, string url)
{
progressBar.Progress = 0;
}
}
public override bool OnKeyDown(Android.Views.Keycode keyCode, Android.Views.KeyEvent e)
{
if (keyCode == Keycode.Back && webview.CanGoBack())
{
webview.GoBack();
return true;
}
return base.OnKeyDown(keyCode, e);
}
}
}

This is the Working Code of File Upload Hope this will Help you
public class MyWb : Activity
{
int count = 1;
IValueCallback mUploadMessage;
private static int FILECHOOSER_RESULTCODE = 1;
protected override void OnCreate (Bundle bundle)
{
base.OnCreate (bundle);
// Set our view from the "main" layout resource
SetContentView (Resource.Layout.Main);
// Get our button from the layout resource,
// and attach an event to it
Button button = FindViewById<Button> (Resource.Id.myButton);
button.Click += delegate {
button.Text = string.Format ("{0} clicks!", count++);
};
var chrome = new FileChooserWebChromeClient ((uploadMsg, acceptType, capture) => {
mUploadMessage = uploadMsg;
var i = new Intent (Intent.ActionGetContent);
i.AddCategory (Intent.CategoryOpenable);
i.SetType ("image/*");
StartActivityForResult (Intent.CreateChooser (i, "File Chooser"), FILECHOOSER_RESULTCODE);
});
var webview = this.FindViewById<WebView> (Resource.Id.webView1);
webview.SetWebViewClient (new WebViewClient ());
webview.SetWebChromeClient (chrome);
webview.Settings.JavaScriptEnabled = true;
webview.LoadUrl ("http://www.script-tutorials.com/demos/199/index.html");
}
protected override void OnActivityResult (int requestCode, Result resultCode, Intent intent)
{
if (requestCode == FILECHOOSER_RESULTCODE) {
if (null == mUploadMessage)
return;
Java.Lang.Object result = intent == null || resultCode != Result.Ok
? null
: intent.Data;
mUploadMessage.OnReceiveValue (result);
mUploadMessage = null;
}
}
}
partial class FileChooserWebChromeClient : WebChromeClient
{
Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback;
public FileChooserWebChromeClient (Action<IValueCallback, Java.Lang.String, Java.Lang.String> callback)
{
this.callback = callback;
}
//For Android 4.1
[Java.Interop.Export]
public void openFileChooser (IValueCallback uploadMsg, Java.Lang.String acceptType, Java.Lang.String capture)
{
callback (uploadMsg, acceptType, capture);
}
}

Unable to display and detect bluetooth devices

using Android.App;
using Android.Widget;
using Android.OS;
using Android.Bluetooth;
using Android.Content;
using Android.Views;
namespace BluetoothBLE
{
[Activity(Label = "BluetoothBLE", MainLauncher = true)]
public class MainActivity : Activity
{
//Local Bluetooth adapter
private BluetoothAdapter bluetoothAdapter = null;
//Return Intent extra
public const string Extra_Device_Address = "device_address";
//Members Field
private static ArrayAdapter<string> Device;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
//Get our UI controls from the loaded layout
TextView Text = FindViewById<TextView>(Resource.Id.BluetoothDevices);
TextView Device_Name = FindViewById<TextView>(Resource.Id.DeviceName);
Button Scan = FindViewById<Button>(Resource.Id.Scan);
TextView NewDevice = FindViewById<TextView>(Resource.Id.NewDevice);
ListView List = FindViewById<ListView>(Resource.Id.ListBluetooth);
//Initialize array adapters
Device = new ArrayAdapter<string>(this, Resource.Layout.Main);
//Testing Faced
Scan.Click += (sender, e) =>
{
if (bluetoothAdapter.IsEnabled == true)
{
Toast.MakeText(Application, "Start scanning", ToastLength.Short).Show();
DoDiscovery();
(sender as View).Visibility = ViewStates.Visible;
if(Device.Count != 0)
{
NewDevice.Text = Device.GetItem(0).ToString();
}
else
{
NewDevice.Text = "Device is not recorded";
}
Toast.MakeText(Application, "Device found", ToastLength.Short).Show();
}
else
{
Toast.MakeText(Application, "Please enable bluetooth", ToastLength.Short).Show();
}
};
//Find and set up the ListView for newly discovered devices.
List.Adapter = Device;
List.ItemClick += DeviceListClick;
//Register for broadcasts when a device is discovered
Receiver receiver = new Receiver();
var filter = new IntentFilter(BluetoothDevice.ActionFound);
RegisterReceiver(receiver, filter);
//Register for broadcasts when discovery is finished
filter = new IntentFilter(BluetoothAdapter.ActionDiscoveryFinished);
RegisterReceiver(receiver, filter);
bluetoothAdapter = BluetoothAdapter.DefaultAdapter; //Get Loacl Bluetooth Adapter
if (bluetoothAdapter == null)
{
Toast.MakeText(this, "Bluetooth is not Supported.", ToastLength.Long).Show();
Finish();
return;
}
//Display the Name of local bluetooth
Device_Name.Text = bluetoothAdapter.Name;
}
protected override void OnResume()
{
base.OnResume();
//RegisterReceiver(bluetooth, new IntentFilter(""));
}
protected override void OnPause()
{
base.OnPause();
//UnregisterReceiver(bluetooth);
}
void DeviceListClick (object sender, AdapterView.ItemClickEventArgs args)
{
// Cancel discovery because it's costly and we're about to connect
bluetoothAdapter.CancelDiscovery();
//Get the device MAC address, which is the last 17 chars in the View
var info = (args.View as TextView).Text.ToString();
var address = info.Substring(info.Length - 17);
//Create the result Intent and include the MAC address
Intent intent = new Intent();
intent.PutExtra(Extra_Device_Address, address);
//Set result and finish this Activity
SetResult(Result.Ok, intent);
Finish();
}
private void DoDiscovery()
{
//Indicate scanning in the title
SetProgressBarIndeterminateVisibility(true);
SetTitle(Resource.String.scanning);
//Turn on sub-title for new devices
FindViewById<View>(Resource.Id.NewDevice).Visibility = ViewStates.Visible;
//If we're already discovering, stop it
if (bluetoothAdapter.IsDiscovering)
{
bluetoothAdapter.CancelDiscovery();
}
//Request disccover from BluetoothAdapter
bluetoothAdapter.StartDiscovery();
}
public class Receiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
string action = intent.Action;
// When discovery finds a device
if (action == BluetoothDevice.ActionFound)
{
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = (BluetoothDevice)intent.GetParcelableExtra(BluetoothDevice.ExtraDevice);
// If it's already paired, skip it, because it's been listed already
if(device.BondState != Bond.Bonded)
{
Device.Add(device.Name + "\n" + device.Address);
}
// When discovery is finished, change the Activity title
else if(Device.Count == 0)
{
Device.Add("Empty");
}
}
}
}
}
}
Testing my code, I found out that my application is unable to detect Bluetooth devices and also it is unable to display them. I went online to find examples to follow and did not find anything wrong. Any helps would be greatly appreciated. Apologies if I made small mistakes, this is my first time trying to create android application using Xamarin.

Xamarin.Droid Firebase with Facebook Authentication

After hours of research on this, I have been trying to get this done. I have made further and some necessary improvement and this is what i have. I am able to successfully login but what i want to do next is to let Firebase display the logged users. That is what i have been struggling with for some hours now.
When i take out this line out of my code firebaseAuth.SignInWithCredential(credential).AddOnCompleteListener(this, new IOnCompleteListener<IAuthResult>());, I am able to login successfully but user doesn't show on Firebase.
But when i include the line firebaseAuth.SignInWithCredential(credential).AddOnCompleteListener(this, new IOnCompleteListener<IAuthResult>());, i get System.NullReferenceException has been thrown and i actually don't know where the error is coming from. Please help.
Thank you.
public class LoginActivity : BaseActivity, IFacebookCallback, IAuthStateListener, IOnCompleteListener
{
private ICallbackManager mCallbackManager;
private Firebase.Auth.FirebaseAuth firebaseAuth;
private IOnCompleteListener listener;
public static FirebaseApp app;
private Firebase.Auth.FirebaseAuth.IAuthStateListener firebaseAuthListener;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
FacebookSdk.SdkInitialize(this.ApplicationContext);
LoginButton button = FindViewById<LoginButton>(Resource.Id.login_button);
button.SetReadPermissions("email","public_profile");
mCallbackManager = CallbackManagerFactory.Create();
button.RegisterCallback(mCallbackManager, this);
}
public void handleFacebookAccessToken(AccessToken accessToken)
{
AuthCredential credential = FacebookAuthProvider.GetCredential(accessToken.Token);
firebaseAuth.SignInWithCredential(credential).AddOnCompleteListener(this, new IOnCompleteListener<IAuthResult>());
}
public void OnAuthStateChanged(Firebase.Auth.FirebaseAuth auth)
{
FirebaseUser user = firebaseAuth.CurrentUser;
if (user != null)
{
Console.WriteLine("The current user is " + firebaseAuth.CurrentUser);
}
Console.WriteLine("The current user is " + firebaseAuth.CurrentUser);
}
public void OnCancel()
{
throw new NotImplementedException();
}
public void OnError(FacebookException p0)
{
throw new NotImplementedException();
}
public void OnSuccess(Java.Lang.Object result)
{
LoginResult loginResult = result as LoginResult;
handleFacebookAccessToken(loginResult.AccessToken);
Console.WriteLine("My token is" + loginResult.AccessToken);
}
protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
base.OnActivityResult(requestCode, resultCode, data);
mCallbackManager.OnActivityResult(requestCode, (int)resultCode, data );
}
protected override void OnStart(){
base.OnStart();
// firebaseAuth.AddAuthStateListener(firebaseAuthListener);
}
protected override void OnStop(){
base.OnStop();
// firebaseAuth.RemoveAuthStateListener(firebaseAuthListener);
}
private class IOnCompleteListener<T> : IOnCompleteListener
{
public IntPtr Handle => throw new NotImplementedException();
public void Dispose()
{
throw new NotImplementedException();
}
public void OnComplete(Android.Gms.Tasks.Task task)
{
if (!task.IsSuccessful)
{
}
else
{
}
}
}
}
}

I saw that you've tried to implement IOnCompleteListener for your LoginActivity, but I didn't find public void OnComplete(Task task) in your code, please make sure that you've implemented the Android.Gms.Tasks.IOnCompleteListener, and if you do this, you can simply change your code firebaseAuth.SignInWithCredential(credential).AddOnCompleteListener(this, new IOnCompleteListener<IAuthResult>()); to firebaseAuth.SignInWithCredential(credential).AddOnCompleteListener(this, this);.
Following is my demo, it works by my side:
[Activity(Label = "Activity3", Exported = true)]
[IntentFilter(new[] { Intent.ActionView },
DataScheme = "#string/fb_login_protocol_scheme"),]
public class Activity3 : Activity, IFacebookCallback, IOnCompleteListener
{
private ICallbackManager mCallbackManager;
private FirebaseAuth mAuth;
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
FacebookSdk.SdkInitialize(this.ApplicationContext);
// Create your application here
SetContentView(Resource.Layout.layout3);
FirebaseApp.InitializeApp(this);
mAuth = FirebaseAuth.Instance;
LoginButton fblogin = FindViewById<LoginButton>(Resource.Id.fblogin);
fblogin.SetReadPermissions("email", "public_profile");
mCallbackManager = CallbackManagerFactory.Create();
fblogin.RegisterCallback(mCallbackManager, this);
}
private void handleFacebookAccessToken(AccessToken accessToken)
{
AuthCredential credential = FacebookAuthProvider.GetCredential(accessToken.Token);
mAuth.SignInWithCredential(credential).AddOnCompleteListener(this, this);
}
//facebook IFacebookCallback implementation
public void OnSuccess(Java.Lang.Object p0)
{
LoginResult loginResult = p0 as LoginResult;
handleFacebookAccessToken(loginResult.AccessToken);
}
public void OnCancel()
{
}
public void OnError(FacebookException p0)
{
}
//firebase IOnCompleteListener implementation
public void OnComplete(Task task)
{
if (task.IsSuccessful)
{
FirebaseUser user = mAuth.CurrentUser;
}
else
{
Toast.MakeText(this, "Authentication failed.", ToastLength.Short).Show();
}
}
// acitivity lifecycle
protected override void OnStart()
{
base.OnStart();
FirebaseUser currentUser = mAuth.CurrentUser;
}
protected override void OnActivityResult(int requestCode, [GeneratedEnum] Result resultCode, Intent data)
{
base.OnActivityResult(requestCode, resultCode, data);
var resultCodeNum = 0;
switch (resultCode)
{
case Result.Ok:
resultCodeNum = -1;
break;
case Result.Canceled:
resultCodeNum = 0;
break;
case Result.FirstUser:
resultCodeNum = 1;
break;
}
mCallbackManager.OnActivityResult(requestCode, resultCodeNum, data);
}
}

Xamarin Android Background Service crashes when the Application get closed

Hello, I want to build an app, in which you can start a service, which runs intependenly and creates a notification, and this service should constantly proof, if the DateTime.Now.Date is bigger than a spezific Date.
When I execute the code below, the notification gets displayed, but when I am closing the app, a few secondes later I get two times an information that the app crashed and I dont know why.
I cant even debug the code because this anly happens when the application is closed....
I hope you can help me thanks!
Here is my code:
namespace App
{
[Activity(Label = "App", MainLauncher = true, Icon = "#drawable/icon")]
public class MainActivity : Activity
{
int count = 1;
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
// Set our view from the "main" layout resource
SetContentView(Resource.Layout.Main);
// Get our button from the layout resource,
// and attach an event to it
Button button = FindViewById<Button>(Resource.Id.MyButton);
button.Click += delegate {
button.Text = string.Format("{0} clicks!", count++);
StartService(new Intent(this, typeof(backgroudservice)));
};
}
}
public class backgroudservice : Service
{
public override IBinder OnBind(Intent intent)
{
return null;
}
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
newnotification("Title", "Text: ", 0);
new Task(() => {
DoWork();
Thread.Sleep(1000);
}).Start();
return StartCommandResult.Sticky;
}
public void DoWork()
{
if (DateTime.Now.Date > Convert.ToDateTime("2016-03-29").Date)
{
cancelnotification(0);
StopSelf();
}
}
public override void OnDestroy()
{
base.OnDestroy();
cancelnotification(0);
}
private void newnotification(string titel, string text, int id)
{
Notification.Builder builder = new Notification.Builder(this)
.SetContentTitle(titel)
.SetContentText(text)
.SetSmallIcon(Resource.Drawable.droidlogo_small)
.SetAutoCancel(false)
.SetVisibility(NotificationVisibility.Public)
.SetContentIntent(PendingIntent.GetActivity(this, 0, new Intent(this, typeof(MainActivity)), PendingIntentFlags.OneShot));
// Build the notification:
Notification notification = builder.Build();
notification.Flags = NotificationFlags.NoClear;
//notification.ContentIntent = new Intent(this,typeof(login));
// Get the notification manager:
NotificationManager notificationManager = GetSystemService(Context.NotificationService) as NotificationManager;
// Publish the notification:
notificationManager.Notify(id, notification);
}
private void cancelnotification(int id)
{
NotificationManager notificationManager = GetSystemService(Context.NotificationService) as NotificationManager;
notificationManager.Cancel(id);
}
}
}

I solved it, I forgot the [Service] above my class, now it works!
[Service]
public class backgroudservice : Service
{
...
}

You might try moving the call to cancelnotification in your service's OnDestroy to before the call to the base method, i.e.:
public override void OnDestroy()
{
cancelnotification(0);
base.OnDestroy();
}

Collecting GPS co-Ordinates

I am building a native android app using xamarin. The issue is, that the application collects and displays the coordinates perfectly on the emulator but when I put it on a smartphone (tried 2 samsung phones) it comes up with can't determine the current address. Extra information data and locations are turned on so I am not sure where the issue is. Thanks for your help. here is the xammarin recipe encase that helps https://developer.xamarin.com/recipes/android/os_device_resources/gps/get_current_device_location/
[Activity(Label = "NewRoute")]
public class NewRouteActivity : Activity, ILocationListener
{
static readonly string TAG = "X:" + typeof(NewRouteActivity).Name;
TextView _addressText;
Location _currentLocation;
LocationManager _locationManager;
string _locationProvider;
TextView _locationText;
public async void OnLocationChanged(Location location) {
_currentLocation = location;
if (_currentLocation == null)
{
_locationText.Text = "Unable to determine your location. Try again in a short while.";
}
else
{
_locationText.Text = string.Format("{0:f6},{1:f6}", _currentLocation.Latitude, _currentLocation.Longitude);
Address address = await ReverseGeocodeCurrentLocation();
DisplayAddress(address);
}
}
public void OnProviderDisabled(string provider) { }
public void OnProviderEnabled(string provider) { }
public void OnStatusChanged(string provider, Availability status, Bundle extras) { }
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.CreatetRoute);
_addressText = FindViewById<TextView>(Resource.Id.address_text);
_locationText = FindViewById<TextView>(Resource.Id.location_text);
FindViewById<TextView>(Resource.Id.get_address_button).Click += AddressButton_OnClick;
InitializeLocationManager();
Button btnEndPoint = FindViewById<Button>(Resource.Id.btnEndPoint);
btnEndPoint.Click += new EventHandler(AfterPointsCollected);
}
//Location Stuff
void InitializeLocationManager()
{
_locationManager = (LocationManager)GetSystemService(LocationService);
Criteria criteriaForLocationService = new Criteria
{
Accuracy = Accuracy.Fine
};
IList<string> acceptableLocationProviders = _locationManager.GetProviders(criteriaForLocationService, true);
if (acceptableLocationProviders.Any())
{
_locationProvider = acceptableLocationProviders.First();
}
else
{
_locationProvider = string.Empty;
}
Log.Debug(TAG, "Using " + _locationProvider + ".");
}
//Override OnResume so that Activity1 will begin listening to the LocationManager when the activity comes into the foreground:
protected override void OnResume()
{
base.OnResume();
_locationManager.RequestLocationUpdates(_locationProvider, 0, 0, this);
}
async void AddressButton_OnClick(object sender, EventArgs eventArgs)
{
if (_currentLocation == null)
{
_addressText.Text = "Can't determine the current address. Try again in a few minutes.";
return;
}
Address address = await ReverseGeocodeCurrentLocation();
DisplayAddress(address);
}
async Task<Address> ReverseGeocodeCurrentLocation()
{
Geocoder geocoder = new Geocoder(this);
IList<Address> addressList =
await geocoder.GetFromLocationAsync(_currentLocation.Latitude, _currentLocation.Longitude, 10);
Address address = addressList.FirstOrDefault();
return address;
}
void DisplayAddress(Address address)
{
if (address != null)
{
StringBuilder deviceAddress = new StringBuilder();
for (int i = 0; i < address.MaxAddressLineIndex; i++)
{
deviceAddress.AppendLine(address.GetAddressLine(i));
}
// Remove the last comma from the end of the address.
_addressText.Text = deviceAddress.ToString();
}
else
{
_addressText.Text = "Unable to determine the address. Try again in a few minutes.";
}
}
//Override OnPause and unsubscribe Activity1 from the LocationManager when the activity goes into the background:
protected override void OnPause()
{
base.OnPause();
_locationManager.RemoveUpdates(this);
}
//Changing Activity
void AfterPointsCollected(object sender, EventArgs e)
{
//context //activity
Intent intent = new Intent(this, typeof(AfterPointsCollectedActivity));
//starts the activity with the intent above
this.StartActivity(intent);
}

Your phones are probably running MarshMallow which now require that you request permission for location services.
You can read more about it here https://blog.xamarin.com/requesting-runtime-permissions-in-android-marshmallow/. You might want to use this Nuget package that handles all that for you. https://github.com/jamesmontemagno/Xamarin.Plugins/tree/master/Geolocator