Xamarin Forms multiple instances of same app open

Research:

Are you having an issue where multiple instances of a Xamarin Forms app can launch and sometimes on top of each other? The issue is usually caused when the application is already running and the app gets launched again from the home screen rather than the recent applications menu.

After some Googling, you might find answers such as these:

https://stackoverflow.com/questions/4341600/how-to-prevent-multiple-instances-of-an-activity-when-it-is-launched-with-differ

You might also come across answers where people tell you to set the launch mode in the application manifest mode. These people would be pretty close to the actual answer, but in actual reality, the application manifest for Android within Xamarin Forms doesn't seem to affect the behavious of the app in regards to it's launch mode.

That's when I started looking into the actual documentation for launch mode on Xamarin Forms, and after reading up on the subject here:

https://developer.xamarin.com/api/type/Android.App.ActivityAttribute/ 

The fix:

It turns out that this indeed the fix, but it's not the applications manifest that you need to modify, it's the MainActivity class. See my example below Where I set 'LaunchMode = LaunchMode.SingleInstance'.

[Activity(Label = "My App Name", Icon = "@drawable/icon", Theme = "@style/MainTheme", MainLauncher = false, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation, LaunchMode = LaunchMode.SingleInstance)]
public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
{
    ....
}


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Tags: Xamarin,Xamarin Forms,Android,C#

Luke Alderton

Comments

Shane
Thanks! Exactly what I was looking for.
14/12/2018
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