Think of it this way: there's iTunes on Windows, but is it actually useful? In reality, it's buggy as hell, slow as hell, quite resource-hungry and requires hundreds of megabytes to install it (even though it's nothing more than a music player capable of being connected to other devices). And Windows version of iTunes contains a Windows port for years.

Now, if Apple actually released the code of its Windows port of iTunes, will Apple actually care about it enough to accept the contributions from the community and make the community feel welcome? Will iTunes on Windows drastically improve as the time goes on? Will developers on other platforms accept it and use it for their products? How well does it behave when compared to other programming languages? There are too many unknowns.

Although I'd love to see that future, I don't think that this will happen. In theory, releasing the code of something is all that is needed to do to make something actually useful. In reality, things are not that simple.

Not even a year, about a month. Swift for Linux will arrive with the release of Swift 2.0, which will coincide with the release of Xcode 7, which will coincide with the release of iOS 9 ... which will coincide with the announcement of the next iPhone, which should be around late September, as usual.

It came out wrong, but I was thinking about Visual Basic .NET and C# .NET. Not sure about the others since I never tried them. Thanks for pointing that out, I'll edit my comment.