Relationship between Universal Windows App and .NET Framework version

Question

In Visual Studio 2015, in the New Project dialog box, above the "Blank App (Universal Windows)" template name there is a combo box where you can select the .NET Framework version.

By default .NET Framework version 4.5.2 is selected, and most screenshots in tutorials and guides show this version as selected. However, there is also .NET Framework 4.6 in the list that can be selected.

What would be the difference if I select .NET Framework 4.6? Can I use any new APIs and/or any C# language improvements in an Universal Windows App?

And will the app only run on Windows systems that have the .NET Framework 4.6 installed?

Answer 1

And will the app only run on Windows systems that have the .NET Framework 4.6 installed?

No, it runs on any machine or device that's capable of running Universal apps. The framework version number detail disappears once the Store packages your app, the framework methods you actually use are compiled into the package. Done by .NET Native, the ahead-of-time compiler for Universal apps. The package even runs on a device that doesn't have the .NET Framework installed at all, like a phone.

So the framework you select doesn't matter. Picking 4.5.1 or 4.5.2 or 4.6 doesn't give you extra capabilities, those runtime revisions had very few new api additions in the first place. But above all you build your project with reference assemblies that doesn't expose them. Note how you can pick 3.5 in the combobox and it makes no difference.

Review Project > Properties > Application tab. That's what really matters, you target a Universal version. Currently only build 10240 so nothing to fret about, yet. The framework version that targets is a subset of the .NET Framework you have on your machine, named .NETCore. It is a lot smaller than the full version.

Don't forget to test your Release build, very important to .NET Native.