Xamarin Message Center Multiple Of The Same Message Different Results

Question

I'm making a timer app, so backgrounding is super important. The way I am doing it is through this method outlined in this link. https://robgibbens.com/backgrounding-with-xamarin-forms/ Basically a loop of Ticked messages and updating the view.

The issue is I want to have multiple timers running at once. This confuses my program and the timers start receiving eachothers' messages. Any idea how you can send messages privately in the message center between one class and the AppDelegate.cs and MainActivity.cs classes?

Thanks

score 0 · Accepted Answer · answered Aug 20 '20 at 06:44

You can set different message names for MessagingCenter, like following code. One Message called OneMessage, the other message called TwoMessage,

 private void TimerUp(object sender, ElapsedEventArgs e)
        {
            currentCount += 1;
            MessagingCenter.Send<App, string>(App.Current as App, "OneMessage", currentCount.ToString());
            currentCount2 += 2;
            MessagingCenter.Send<App, string>(App.Current as App, "TwoMessage", currentCount2.ToString());
        }

When we recevice the MessagingCenter, we can use MessageName to distinguish them

  MessagingCenter.Subscribe<App, string>(App.Current, "OneMessage", (snd, arg) =>
            {
                Device.BeginInvokeOnMainThread(() => {
                   //we can get the information by arg
                    myLabel.Text = arg;
                });
            });

            MessagingCenter.Subscribe<App, string>(App.Current, "TwoMessage", (snd, arg) =>
            {
                Device.BeginInvokeOnMainThread(() => {
                  //we can get the information by arg
                    myLabel2.Text = arg;
                });
            });

Here is running gif.

Here is my demo.

https://github.com/851265601/MessageCenterDemo

I notice you want to make the background service always running. Due to Android 8.0 limiation. Normal service will be killed if Application in the background. So I advice you to use Foreground service to keep the service always running.

https://learn.microsoft.com/en-us/xamarin/android/app-fundamentals/services/foreground-services

Here is my demo about foreground service.

https://github.com/851265601/ForeGroundService

If above answer is helpful, please do not forget to accept it as answer(click the “✔” in the upper left corner of this answer), it will help others who have similar issue — Leon, Aug 20 '20 at 06:44
Thank you for the response! I ended up implementing several different messages, and initiating more subscriptions with a unique, stored string. This way I can have as many timers as I want. Will iOS also have issues with background service? Do you have any recommendations? I’m trying to allow the user to set as many timers as they want independently, and when I call stopService on Android, it stops every service too. Would using foreground services fix this? — Bloodred566, Aug 21 '20 at 07:07

Xamarin Message Center Multiple Of The Same Message Different Results

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