Messeging center hits multiple times when sending from Shared code to platform code- Xamarin.forms - xamarin

Question

I know these questions asked several times on SO. But I can't able to solve this. In my xamarin.forms app, I am showing a camera inside one page using custom Camera View. The button for taking a picture is in a shared code. For taking a picture from shared code, I am using the Messaging Center. When we click the button the messaging center send from shared code will subscribe to my camera custom Render and picture taking action will happen.
The problem I am facing is the subscribing part of the Messaging center will hit multiple times. The weird thing is the subscribing will increase each time when we click the button. I added the Unsubscribe messaging center. Then it will no longer hit. What will be the cause of this problem? Any help is appreciated.
My shared code Portion where messaging center send.
private async void Capture_Tapped(object sender, EventArgs e)
{
try
{
MessagingCenter.Send<CameraPopup>(this, "CaptureClick");
}
catch (Exception)
{
}
}
Messeging center subscribing portion on android Camera Custom render
protected async override void OnElementChanged(ElementChangedEventArgs<Centraverse.Views.Clocking.CustomCamera.CameraPreview> e)
{
base.OnElementChanged(e);
if (Control == null)
{
cameraPreview = new CameraPreview(Context);
SetNativeControl(cameraPreview);
// This portion hitting multiple times
MessagingCenter.Subscribe<CameraPopup>(this,"CaptureClick", (sender) =>
{
try
{
Log.Info("Reached here:","Try catch of first ");
if (DetectedFaceCount == 0)
{
//Do Action
}
else if (DetectedFaceCount == 1)
{
Control.Preview.StopFaceDetection();
Task.Run(() => takepicture());
}
else if (DetectedFaceCount > 1)
{
//Do Action
}
}
catch (Exception ex)
{
return;
}
// MessagingCenter.Unsubscribe<CameraPopup>(this, "CaptureClick");
});
}
if (e.OldElement != null)
{
}
if (e.NewElement != null)
{
try
{
Control.Preview = Camera.Open((int)e.NewElement.Camera);
Device.BeginInvokeOnMainThread(async () =>
{
Control.Preview.SetFaceDetectionListener(this);
Control.Preview.StartFaceDetection();
});
}
catch (Exception ex)
{
return;
}
}
}

Answer 1

According to your description and to the code there can be just one reason for this - you are subscribing multiple times to the event. So you need to unsubscribe first or to have some internal tracking mechanism that you have subscribed and to do it just once.