.app application bundle. To make .NET Core and Avalonia projects work in a .app bundle, some extra legwork has to be done after your application has gone through the publishing process..app folder structure that looks like this:.app file/folder structure. You can do this on any operating system, since a .app file is just a set of folders laid out in a specific format and the tooling isn't specific to one operating system. However, if you build on Windows outside of WSL, the executable may not have the right attributes for execution on macOS -- you may have to run chmod +x on the published binary output (the output generated by dotnet publish) from a Unix machine. This is the binary output that ends up in the folder MyApp.app/Contents/MacOS/, and the name should match CFBundleExecutable..app structure relies on the Info.plist file being properly formatted and containing the right information. Use Xcode to edit Info.plist, it has auto-completion for all properties. Make sure that:CFBundleExecutable matches the binary name generated by dotnet publish -- typically this is the same as your .dll assembly name without .dll.CFBundleName is set to the display name for your application. If this is longer than 15 characters, set CFBundleDisplayName too.CFBundleIdentifier is set to a unique identifier, typically in reverse-DNS format -- e.g. com.myapp.macos.CFBundleShortVersionString is set to the user-visible string for your application's version, e.g. Major.Minor.Patch.osx-64, add the following runtime identifiers to the top <PropertyGroup> in your .csproj:.app executable file.app bundle will not have the standard .dll extension. If your publish folder contents, which go inside the .app bundle, do not have both a MyApp (exectuable) and a MyApp.dll, things are probably not generating properly, and macOS will probably not be able to start your .app properly.MyApp executable (also called the "app host" in the linked documentation) to not be generated. You need this file to be generated in order for your .app to function properly. To make sure this gets generated, do one of the following:.csproj file:-p:UseAppHost=true to your dotnet publish command..app file for you.PackageReference in your project. Add it to your project via NuGet package manager or by adding the following line to your .csproj file:.app by executing the following on the command line:dotnet msbuild command. For instance, if you want to publish in release mode:CFBundleDisplayName, etc., on the command line, you can also specify them in your project file:dotnet-bundle will put the .app file in the same place as the publish output: [project directory]/bin/{Configuration}/netcoreapp3.1/osx-x64/publish/MyBestThingEver.app..app on Windows, make sure to run chmod +x MyApp.app/Contents/MacOS/AppName from a Unix machine. Otherwise, the app will not start on macOS.Info.plist file, adding or modifying keys as necessary:.app folder structure as outlined at the top of this page. If you want a script to do it for you, you can use something like this (macOS/Unix):.app on Windows, make sure to run chmod +x MyApp.app/Contents/MacOS/AppName from a Unix machine. Otherwise, the app will not start on macOS..app file created, you'll probably want to sign your app so that it can be notarized and distributed to your users without Gatekeeper giving you a hassle. Notarization is required for apps distributed outside the app store starting in macOS 10.15 (Catalina), and you'll have to enable hardened runtime and run codesign on your .app in order to notarize it successfully.codesign command line tool that comes with Xcode..app bundle under the Contents/MacOS folder, which is easiest to do with a script since there are a lot of files. In order to sign your files, you need an Apple developer account. In order to notarize your app, you'll need to do the following steps with a Developer ID certificate, which requires a paid Apple developer subscription.xcode-select --install on the command line and following the prompts to install the tools--options=runtime part of the codesign line is what enables the hardened runtime with your app. Because .NET Core may not be fully compatible with hardened runtime, we add some exceptions to use JIT-compiled code and allow for Apple Events to be sent. The JIT-compiled code exception is required to run Avalonia apps under hardened runtime. We add the second exception for Apple Events to fix an error that shows up in Console.app.com.apple.security.cs.allow-jit. The others may impose security risks with your application. Use with caution.xcrun altool, check out Apple's documentation..app is code signed properly.app in a .zip file, e.g. MyApp.zip.xcrun altool --notarize-app -f MyApp.zip --primary-bundle-id com.unique-identifier-for-this-upload -u username -p password. You can use a password in your keychain by passing -p "@keychain:AC_PASSWORD", where AC_PASSWORD is the key. The account has to be registered as an Apple Developer.28fad4c5-68b3-4dbf-a0d4-fbde8e6a078fxcrun altool --notarization-info 28fad4c5-68b3-4dbf-a0d4-fbde8e6a078f -u username -p password. This could take some time -- eventually it will succeed or fail.xcrun stapler staple MyApp.app. You can validate this by running xcrun stapler validate MyApp.app..dmg, you will want to modify the steps slightly:.app as normal (in a .zip file)xcrun stapler) app into the DMG (the DMG now has the notarized/stapled .app file inside of it)..dmg file (same basic xcrun altool command, just with the .dmg file for the -f flag instead of the .zip).dmg file: xcrun stapler staple MyApp.dmg3rd Party Mac Developer Installer for signing .pkg file and Apple Distribution for signing all files in .app..app and other for signing all files inside .app..app structure ready with valid Info.plist.3rd Party Mac Developer Installer and Apple Distribution. If cert names are started with another strings - you've created a wrong certificate. Try again.Allow all applications to access this item in case you don't want to enter a mac profile password for every file sign..app/Content/MacOS/ folder. It should look like this..app into Applications folder and launch it. If it launches correctly - you did everything right. If it crashes - open Console app and check a crash report.