Hands-On Mobile Development with .NET Core

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Creating a runtime agnostic application

To begin with, we will create our console application on macOS that has .NET Core installed:

$ mkdir demo && cd $_
$ dotnet --version
2.1.301
$ dotnet new console
The template "Console Application" was created successfully.

Processing post-creation actions...
Running 'dotnet restore' on /demo/demo.csproj...
 Restoring packages for /demo/demo.csproj...
 Generating MSBuild file /demo/obj/demo.csproj.nuget.g.props.
 Generating MSBuild file /demo/obj/demo.csproj.nuget.g.targets.
 Restore completed in 236.91 ms for /demo/demo.csproj.

Restore succeeded.

In this example, we have used the console template, but there are many other templates available out of the box, such as class library, unit test project, asp.net core, as well as more specific templates, such as razor page or MVC ViewStart.

Now, the helloworld console application should have been created in the folder that you specified in the first step.

In order to restore the NuGet packages associated with any project, you can use the dotnet restore command in a command line or Terminal window, depending on your operating system.

Generally, you don't need to use the restore command, as the compilation already does this for you. In the case of template creation, the last step actually restores the NuGet packages.

Now that our application project is ready (after editing the program.cs file), we can build and run the console application:

Here, we used the run command to compile and run our application in the current platform (macOS). If you were to navigate to the build folder, you would notice that, instead of an executable, the CLI actually created a Dynamic Link Library (DLL) file. The reason for this is that, since no other compilation option was defined, the application was created as a framework-dependent application. We can try running the application with the dotnet command, which is called the driver:

$ cd bin/Debug/netcoreapp2.1/
$ ls
demo.deps.json demo.pdb demo.runtimeconfig.json 
demo.dll demo.runtimeconfig.dev.json 
$ dotnet demo.dll
Hello .NET Core

Here, it is important to note that we used the description framework-dependent (in this case, the NETCore.App 2.1 runtime). If we were discussing the .NET framework prior to .NET Core, this would strictly refer to the Windows platform. In this context, however, it refers to an application that is only dependent on the framework itself while being platform-agnostic. In order to test our application on Windows, we can copy the bin folder to a Windows machine with the target framework installed and try running our application:

In order to verify that the required framework is installed on the target machine, you can use the dotnet --info or dotnet --list-sdks commands, which will list the installed runtimes on the target machine.

In order to test the runtime independence of the created demo.dll file, we can try running it with the mono runtime. On macOS, you can try the following command to execute our application:

$ cd bin/Debug/netcoreapp2.1/
$ mono demo.dll
Hello .NET Core