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
{
    ....
}


Published at

Tags: Xamarin,Xamarin Forms,Android,C#

Luke Alderton

Comments

Shane
Thanks! Exactly what I was looking for.
14/12/2018
cxfranco
Excellent, Good article. Thanks
18/01/2019
steve choi
wow thank you very much
30/06/2019
Mahmoud Radwan
Thanks Thanks Thanks
16/09/2019
Chris Boot
Thanks - you've saved me a tonne of pain!
26/01/2020
Mikko Seittenranta
Thanks - that helped
16/02/2021
Share with
Tags
Latest Comments
By Mark Gentry on Windows Server 2019 - Change product key does nothing
20 Aug 2021, 03:30 AM
By Cathy on In-Place Upgrade for a Windows Server domain controller
31 Jul 2021, 18:28 PM
By Mr. Greymatter on Raspberry Pi - Running Java app on Raspbian
16 Feb 2021, 07:35 AM
By Mikko Seittenranta on Xamarin Forms multiple instances of same app open
16 Feb 2021, 04:34 AM
By Andrew on Auto/Custom height on Xamarin Forms WebView for Android and iOS
22 Jan 2021, 22:15 PM
By Nick on Raspberry Pi - Running Java app on Raspbian
14 Oct 2020, 19:37 PM
By Ivan on Fixed: Value cannot be null Parameter Name: source
15 Sep 2020, 19:47 PM
By Anand on Raspberry Pi - Bluetooth using Bluecove on Raspbian
7 Sep 2020, 16:53 PM
Categories
App Development
Event
Game Development
Mapping
Modelling
Programming
Review
Robotics
Tutorial
Web Development