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How to run the UI Grafik and reader function without letting the UI get stopped until function ends? [duplicate]

I have a button that after I click it send a lot of data in a remote database with a loop, but during this operation whole wpf UI is freezing. My goal is to make the loader work while it is processing everything with the database.
My button code:
private void btn_Start_Click(object sender, RoutedEventArgs e)
{
pb_loader.IsIndeterminate = true; //<- it has to start to make animation
IEmailService emailService = new EmailService();
IUserQueryService emailQueryService = new UserQueryService();
var idIniziale = int.Parse(txtIdIniziale.Text);
var idFinale = int.Parse(txtIdFinale.Text);
var n = idFinale - idIniziale;
string mail = "";
for(int i=0; i<=n; i++)
{
mail = txtMail.Text + idIniziale + "#mail.local";
var exist = emailQueryService.CheckUserExist(mail); //<- db operation method
if (exist == false)
{
var lastUniqueId = emailQueryService.GetLastUniqueId();//<- db operation method
lastUniqueId = lastUniqueId + 1;
var idUtente = emailService.SalvaUtente(mail, lastUniqueId); //<- db operation method
emailService.AssegnaReferente(idUtente, txtMail.Text);//<- db operation method
emailService.AssegnaRuoli(idUtente); //<- db operation method
}
idIniziale++;
}
pb_loader.IsIndeterminate = false; //<- it has to end animation of loading
}

One straighforward approach for running a background operation in an event handler is to declare the event handler async and run and await a Task:
private async void btn_Start_Click(object sender, RoutedEventArgs e)
{
// prevent click while operation in progress
btn_Start.IsEnabled = false;
pb_loader.IsIndeterminate = true;
// access UI elements before running the Task
var mail = txtMail.Text + idIniziale + "#mail.local";
...
await Task.Run(() =>
{
// perform background operation
// use local variables "mail" etc. here
});
pb_loader.IsIndeterminate = false;
btn_Start.IsEnabled = true;
}

How to run in-process background task when the app is killed in UWP?

I want my in-process background task to run when the app is killed. This is to constantly track the user's location changes. Not geofencing. So, is there a way to do this in UWP? Following is my code and it gets killed when the app is killed. It took only a few minutes to do this on Android (Sticky background service) & iOS. Using a WindowsRuntimeComponent with out of process task is not possible because I have a lot of code to refer from my Xamarin Forms PCL. The equivalent of what I'm looking for is Android Sticky Background Service.
private async void RegisterBackgroundTask()
{
var backgroundAccessStatus = await BackgroundExecutionManager.RequestAccessAsync();
if (backgroundAccessStatus == BackgroundAccessStatus.AllowedSubjectToSystemPolicy)
{
UnregisterTask(TaskName);
RegisterTask(TaskName);
}
}
private async void RegisterTask(string taskName)
{
BackgroundTaskBuilder taskBuilder = new BackgroundTaskBuilder
{
Name = taskName,
};
var trigger = new ApplicationTrigger();
taskBuilder.SetTrigger(trigger);
var registration = taskBuilder.Register();
await trigger.RequestAsync();
}
protected override void OnBackgroundActivated(BackgroundActivatedEventArgs args)
{
Debug.WriteLine("Background " + args.TaskInstance.Task.Name + " Starting...");
SendToast("Hi this is background Task");
//
// Query BackgroundWorkCost
// Guidance: If BackgroundWorkCost is high, then perform only the minimum amount
// of work in the background task and return immediately.
//
var cost = BackgroundWorkCost.CurrentBackgroundWorkCost;
var settings = ApplicationData.Current.LocalSettings;
settings.Values["BackgroundWorkCost"] = cost.ToString();
//
// Associate a cancellation handler with the background task.
//
args.TaskInstance.Canceled += new BackgroundTaskCanceledEventHandler(OnCanceled);
//
// Get the deferral object from the task instance, and take a reference to the taskInstance;
//
_deferral = args.TaskInstance.GetDeferral();
_taskInstance = args.TaskInstance;
_periodicTimer = ThreadPoolTimer.CreatePeriodicTimer(new TimerElapsedHandler(PeriodicTimerCallback), TimeSpan.FromSeconds(1));
}
private void OnCanceled(IBackgroundTaskInstance sender, BackgroundTaskCancellationReason reason)
{
//
// Indicate that the background task is canceled.
//
_cancelRequested = true;
_cancelReason = reason;
SendToast("Background " + sender.Task.Name + " Cancel Requested...");
}
private void PeriodicTimerCallback(ThreadPoolTimer timer)
{
if ((_cancelRequested == false) && (_progress < 100))
{
_progress += 10;
_taskInstance.Progress = _progress;
SendToast("Timer Went Off!!");
}
else
{
_periodicTimer.Cancel();
var key = _taskInstance.Task.Name;
//
// Record that this background task ran.
//
String taskStatus = (_progress < 100) ? "Canceled with reason: " + _cancelReason.ToString() : "Completed";
var settings = ApplicationData.Current.LocalSettings;
settings.Values[key] = taskStatus;
Debug.WriteLine("Background " + _taskInstance.Task.Name + settings.Values[key]);
SendToast(taskStatus);
//
// Indicate that the background task has completed.
//
_deferral.Complete();
}
}
public static void SendToast(string message)
{
var template = ToastTemplateType.ToastText01;
var xml = ToastNotificationManager.GetTemplateContent(template);
var elements = xml.GetElementsByTagName("text");
var text = xml.CreateTextNode(message);
elements[0].AppendChild(text);
var toast = new ToastNotification(xml);
ToastNotificationManager.CreateToastNotifier().Show(toast);
}

Xamarin Forms Play a sound Asynchronously

I can successfully play sounds using Xamarin forms (Android and iOS) however I also need to achieve the following:
I need to await so that if multiple sounds are 'played', one will complete before the next.
I need to return a boolean to indicate whether operation was a success.
Here is my current simplified code (for the iOS platform):
public Task<bool> PlayAudioTask(string fileName)
{
var tcs = new TaskCompletionSource<bool>();
string filePath = NSBundle.MainBundle.PathForResource(
Path.GetFileNameWithoutExtension(fileName), Path.GetExtension(fileName));
var url = NSUrl.FromString(filePath);
var _player = AVAudioPlayer.FromUrl(url);
_player.FinishedPlaying += (object sender, AVStatusEventArgs e) =>
{
_player = null;
tcs.SetResult(true);
};
_player.Play();
return tcs.Task;
}
To test the method, I have tried calling it like so:
var res1 = await _audioService.PlayAudioTask("file1");
var res2 = await _audioService.PlayAudioTask("file2");
var res3 = await _audioService.PlayAudioTask("file3");
I had hoped to hear the audio for file1, then file2, then file3. However I only hear file 1 and the code doesn't seem to reach the second await.
Thankyou

I think your issue here is that the AVAudioPlayer _player was being cleared out before it was finished. If you were to add debugging to your FinsihedPlaying, you'll notice that you never hit that point.
Try these changes out, I made a private AVAudioPlayer to sit outside of the Task
(I used the following guide as a reference https://developer.xamarin.com/recipes/ios/media/sound/avaudioplayer/)
public async void play()
{
System.Diagnostics.Debug.WriteLine("Play 1");
await PlayAudioTask("wave2.wav");
System.Diagnostics.Debug.WriteLine("Play 2");
await PlayAudioTask("wave2.wav");
System.Diagnostics.Debug.WriteLine("Play 3");
await PlayAudioTask("wave2.wav");
}
private AVAudioPlayer player; // Leave the player outside the Task
public Task<bool> PlayAudioTask(string fileName)
{
var tcs = new TaskCompletionSource<bool>();
// Any existing sound playing?
if (player != null)
{
//Stop and dispose of any sound
player.Stop();
player.Dispose();
}
string filePath = NSBundle.MainBundle.PathForResource(
Path.GetFileNameWithoutExtension(fileName), Path.GetExtension(fileName));
var url = NSUrl.FromString(filePath);
player = AVAudioPlayer.FromUrl(url);
player.FinishedPlaying += (object sender, AVStatusEventArgs e) =>
{
System.Diagnostics.Debug.WriteLine("DONE PLAYING");
player = null;
tcs.SetResult(true);
};
player.NumberOfLoops = 0;
System.Diagnostics.Debug.WriteLine("Start Playing");
player.Play();
return tcs.Task;
}

windows phone progress bar while searching location

I try activate a progressbar, while the app is searching for the location (after pressing a button)
how can i solve it the best way?
the best would somehow to get an if else in there, wheater i got (the rigth) data from the geolocator and check that.
private async void Ellipse_Tap (object sender, System.Windows.Input.GestureEventArgs e)
{
Geolocator geolocator = new Geolocator();
//Set his accuracy in Meters
geolocator.DesiredAccuracyInMeters = 50;
try
{
//The await guarantee the calls to be returned on the thread from which they were called
//Since it is call directly from the UI thread, the code is able to access and modify the UI directly when the call returns.
Geoposition geoposition = await geolocator.GetGeopositionAsync(
maximumAge: TimeSpan.FromMinutes(5),
timeout: TimeSpan.FromSeconds(10)
);
//Relativer Nullpunkt
delta_y = geoposition.Coordinate.Latitude - y;
delta_x = geoposition.Coordinate.Longitude - x;
Path.Visibility = Visibility.Visible;
}
//If an error is catch 2 are the main causes: the first is that you forgot to includ ID_CAP_LOCATION in your app manifest.
//The second is that the user doesn't turned on the Location Services
catch (Exception ex)
{
if ((uint)ex.HResult == 0x80004004)
{
MessageBox.Show("Location is disabled in phone settings.");
return;
//Application.Current.Terminate();
}
//else
{
// something else happened during the acquisition of the location
}
}
}

Assuming you are using the ProgressIndicator in the SystemTry, Add the following to the OnNavigatedTo Method
protected override void OnNavigatedTo(NavigationEventArgs e)
{
base.OnNavigatedTo(e);
SystemTray.ProgressIndicator = new ProgressIndicator();
}
Then create this method to set the ProgressIndicator.
private void DisplayProgressIndicator(bool isvisible, string message = "")
{
SystemTray.ProgressIndicator.Text = message;
SystemTray.ProgressIndicator.IsIndeterminate = isvisible;
SystemTray.ProgressIndicator.IsVisible = isvisible;
}
Then use the method created in the Eclips_Tap method.
private async void Ellipse_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
Geolocator geolocator = new Geolocator();
geolocator.DesiredAccuracyInMeters = 50;
try
{
DisplayProgressIndicator(true, "Finding current location..."); // < SET THE PROGRESS INDICATOR
Geoposition geoposition = await geolocator.GetGeopositionAsync(
maximumAge: TimeSpan.FromMinutes(5),
timeout: TimeSpan.FromSeconds(10)
);
delta_y = geoposition.Coordinate.Latitude - y;
delta_x = geoposition.Coordinate.Longitude - x;
Path.Visibility = Visibility.Visible;
DisplayProgressIndicator(false); // << UNSET PROGRESS INDICATOR
}
catch (Exception ex)
{
if ((uint)ex.HResult == 0x80004004)
{
MessageBox.Show("Location is disabled in phone settings.");
return;
}
}
}
Hope this helps..

Waiting on the results of GetGeopositionAsync()

I'm developing a WinPhone 8 App.
On this App there is a Button 'Send SMS'.
When the user clicks on this button two things should happen:
(Method A) Get the geo-coordinate of the current Location (using Geolocator and GetGeopositionAsync).
(Method B) Compose and send an SMS with the geo-coordinate as part of the body.
The Problem: GetGeopositionAsync is an asynchronous method. Before the coordinate is detected (which takes a few seconds) the SMS is sent (of course with no coordinates).
How can I tell Method 2 to wait until the coordinates are available?
OK, here is my code:
When the user presses the button, the coordinates are determined by the first method and the second method sends the SMS which includes the coordinates in its body:
private void btnSendSms_Click(object sender, RoutedEventArgs e)
{
GetCurrentCoordinate(); // Method 1
// -> Gets the coordinates
SendSms(); // Method 2
// Sends the coordinates within the body text
}
The first method GetCurrentCoordinate() looks as follows:
...
private GeoCoordinate MyCoordinate = null;
private ReverseGeocodeQuery MyReverseGeocodeQuery = null;
private double _accuracy = 0.0;
...
private async void GetCurrentCoordinate()
{
Geolocator geolocator = new Geolocator();
geolocator.DesiredAccuracy = PositionAccuracy.High;
try
{
Geoposition currentPosition = await geolocator.GetGeopositionAsync(
TimeSpan.FromMinutes(1),
TimeSpan.FromSeconds(10));
lblLatitude.Text = currentPosition.Coordinate.Latitude.ToString("0.000");
lblLongitude.Text = currentPosition.Coordinate.Longitude.ToString("0.000");
_accuracy = currentPosition.Coordinate.Accuracy;
MyCoordinate = new GeoCoordinate(
currentPosition.Coordinate.Latitude,
currentPosition.Coordinate.Longitude);
if (MyReverseGeocodeQuery == null || !MyReverseGeocodeQuery.IsBusy)
{
MyReverseGeocodeQuery = new ReverseGeocodeQuery();
MyReverseGeocodeQuery.GeoCoordinate = new GeoCoordinate(
MyCoordinate.Latitude,
MyCoordinate.Longitude);
MyReverseGeocodeQuery.QueryCompleted += ReverseGeocodeQuery_QueryCompleted;
MyReverseGeocodeQuery.QueryAsync();
}
}
catch (Exception)
{ // Do something }
}
private void ReverseGeocodeQuery_QueryCompleted(object sender,
QueryCompletedEventArgs<IList<MapLocation>> e)
{
if (e.Error == null)
{
if (e.Result.Count > 0)
{
MapAddress address = e.Result[0].Information.Address;
lblCurrAddress.Text = address.Street + " " + address.HouseNumber + ",\r" +
address.PostalCode + " " + address.City + ",\r" +
address.Country + " (" + address.CountryCode + ")";
}
}
}
}
And the Methode 'SendSms()':
private void SendSms()
{
SmsComposeTask smsComposeTask = new SmsComposeTask();
smsComposeTask.To = "0123456";
smsComposeTask.Body = "Current position: \rLat = " + lblLatitude.Text +
", Long = " + lblLongitude.Text +
"\r" + lblCurrAddress.Text;
// -> The TextBoxes are still empty!
smsComposeTask.Show();
}
The problem is, that all these TextBoxes (lblLatitude, lblLongitude, lblCurrAddress) are still empty when the method SendSms() sets the SmsComposeTask object.
I have to ensure that the TextBoxes are already set BEFORE the method SendSms() starts.

You should almost never mark a method async void unless it's a UI event handler. You're calling an asynchronous method without waiting for it to end. You are basically calling those 2 methods in parallel, so it's clear why the coordinates aren't available.
You need to make GetCurrentCoordinate return an awaitable task and await it, like this:
private async Task GetCurrentCoordinateAsync()
{
//....
}
private async void btnSendSms_Click(object sender, RoutedEventArgs e)
{
await GetCurrentCoordinateAsync();
// You'll get here only after the first method finished asynchronously.
SendSms();
}

This is one of the primary reasons you should avoid async void. void is a very unnatural return type for async methods.
First, make your GetCurrentCoordinate an async Task method instead of async void. Then, you can change your click handler to look like this:
private async void btnSendSms_Click(object sender, RoutedEventArgs e)
{
await GetCurrentCoordinate();
SendSms();
}
Your click handler is async void only because event handlers have to return void. But you should really strive to avoid async void in all other code.

There two things you're doing wrong here:
Using void returning async methods when you need to await on them. This is bad because you can't await on execution of these methods and should only be used when you can't make the method return Task or Task<T>. That's why you're not seeing anything on the text boxes when SendSmsis called.
Mixing UI and non-UI code. You should transfer data between UI and non-UI code to avoid tight coupling between code with different responsibilities. IT also makes it easy to read and debug the code.
ReverseGeocodeQuery does not have an awaitable async API but you can easily make your own:
private async Task<IList<MapLocation>> ReverseGeocodeQueryAsync(GeoCoordinate geoCoordinate)
{
var tcs = new TaskCompletionSource<IList<MapLocation>>();
EventHandler<QueryCompletedEventArgs<IList<MapLocation>>> handler =
(s, e) =>
{
if (e.Cacelled)
{
tcs.TrySetCancelled();
}
else if (e.Error != null)
{
tcs.TrySetException(e.Error);
}
else
{
tcs.TrySetResult(e.Result);
}
};
var query = new ReverseGeocodeQuery{ GeoCoordinate = geoCoordinate };
try
{
query.QueryCompleted += handler;
query.QueryAsync();
return await tcs.Task;
}
finally
{
query.QueryCompleted -= handler;
}
}
This way you'll get full cancellation and error support.
Now let's make the retrieval of the geo coordinate information all in one chunk:
private async Task<Tuple<Geocoordinate, MapLocation>> GetCurrentCoordinateAsync()
{
try
{
var geolocator = new Geolocator
{
DesiredAccuracy = PositionAccuracy.High
};
var currentPosition = await geolocator.GetGeopositionAsync(
TimeSpan.FromMinutes(1),
TimeSpan.FromSeconds(10))
.ConfigureAwait(continueOnCapturedContext: false);
var currentCoordinate = currentPosition.Coordinate;
var mapLocation = await this.ReverseGeocodeQueryAsync(
new GeoCoordinate(
currentCoordinate.Latitude,
currentCoordinate.Longitude));
return Tuple.Create(
currentCoordinate,
mapLocation.FirstOrDefault());
}
catch (Exception)
{
// Do something...
return Tuple.Create(null, null);
}
}
Now the button eventnt handler becomes much more readable:
private void btnSendSms_Click(object sender, RoutedEventArgs e)
{
var info = await GetCurrentCoordinate();
if (info.Item1 != nuil)
{
lblLatitude.Text = info.Item1.Latitude.ToString("0.000");
lblLongitude.Text = info.Item1.Longitude.ToString("0.000");
}
if (info.Item2 != null)
{
var address = info.Item2.Information.Address;
lblCurrAddress.Text = string.Format(
"{0} {1},\n{2} {3},\n{4} ({5})",
address.Street,
address.HouseNumber,
address.PostalCode,
address.City,
address.Country,
address.CountryCode);
}
SendSms(info.Item1, info.Item2);
}
Does this make sense?