I really feel like I shouldn't have to ask a question on SO to get basic information like this, but I can't find a reliable source anywhere.
Is WiX v4 released? In Development? In Beta? Still being designed?
Lots of people seem to already be using WiX v4, as evidenced by SO questions about it. And it has an official release page on the WiX site, without any mention of "Beta" or "Release Candidate", etc: http://wixtoolset.org/releases/v4-0-0-5205/
However, there are no released versions for v4 on GitHub: https://github.com/wixtoolset/wix4/releases
And the Wix homepage still directs you to download v3.
And one of the developer's blogs has a recent post about v4 that uses future-tense language like "will have" and "should support".
But worst of all, the current version of the WiX visual studio integration tools has templates for v4, which makes it seem like v4 is officially supported!
And when you try to build one of these templates the build error is The WiX Toolset v4 build tools must be installed ... To download WiX Toolset v4, see http://wixtoolset.org/releases/ despite the fact that http://wixtoolset.org/releases/ contains downloads exclusively for v3!
This is a crazy amount of mixed messages.
Is there something somewhere that says officially, definitively what state WiX v4 is in?
Answer
From my point of view, WiX 4 is an ambitious rethink of WiX that aims to simplify the authoring and support more then just MSI. That's a bit of a problem for me as I've created an open source project that heavily invests in WiX 3.I've created WiX v4 templates and support but that was just to try to not be too far behind. Not all of it works and the parts that do work I was told was because they simply haven't broken it yet.
I can only speak for myself... I'll probably just stay on v3.x for ever. The v4 development is taking so long that it'll probably really never be done anyways. And if it gets done and is awesome then I'll just have to find a way to update my stuff to use it.
But ya... don't worry about v4 for now. Just grab 3.11 and start coding. Maybe this will help you:
https://github.com/iswix-llc/iswix-tutorials/tree/master/desktop-application