SingleInstanceCore

For single instance applications on .NET Core

NuGet Package: https://www.nuget.org/packages/SingleInstanceCore/

Usage

Note: Usage examples are for WPF and Winforms desktop applications. For other platforms/frameworks, inheritance and initialization should be done accordingly, not exactly like the examples.

The class that handles instance invokation should inherit ISingleInstance and implement OnInstanceInvoked method.

WPF

E.g. in App class (App.xaml.cs):

public partial class App : Application, ISingleInstance
{
	public void OnInstanceInvoked(string[] args)
	{
		// What to do with the args another instance has sent
	}
	// ...
}

Initialization of instance should be done when application is starting, and cleanup method should be called on the exit point of the application.

E.g. in App class (App.xaml.cs):

	private void Application_Startup(object sender, StartupEventArgs e)
	{
		bool isFirstInstance = this.InitializeAsFirstInstance("soheilkd_ExampleIPC");
		if (!isFirstInstance)
		{
			//If it's not the first instance, arguments are automatically passed to the first instance
			//OnInstanceInvoked will be raised on the first instance
			//You may shut down the current instance
			Current.Shutdown();
		}
	}
		
	private void Application_Exit(object sender, ExitEventArgs e)
	{
		//Do not forget to cleanup
		SingleInstance.Cleanup();
	}

Winforms

Winforms doesn't have an Application.cs that could implement the ISingleInstance interface. We have to define one ourselves.

static class Program
{
	[STAThread]
	static void Main(string[] args)
	{
		var app = new YourApplication();

		var isFirstInstance = app.InitializeAsFirstInstance(nameof(YourApplication));
		if (isFirstInstance)
		{
			try
			{
				app.Run();
			}
			finally
			{
				SingleInstance.Cleanup();
			}
		}
	}
}

class YourApplication : ISingleInstance
{
	public void Run()
	{
		Application.SetHighDpiMode(HighDpiMode.SystemAware);
		Application.EnableVisualStyles();
		Application.SetCompatibleTextRenderingDefault(false);
		Application.Run(new MainForm()); // Blocks until the main window is closed
	}

	public void OnInstanceInvoked(string[] args)
	{
		// What to do with the args another instance has sent
	}
}