I'm running UnityVS through Visual Studio, I build the game on OSX Unity and try to attach Visual Studio on Windows to it via 'Attach to Process'.
Nothing happens when I do t his, no output and the debugger does not connect. I can connect to any other player this way and this used to work in previous versions of Unity.
As another interesting tidbit: the iPhonePlayer does not appear in MonoDevelop at all, on Windows Monodevelop sees the iPhonePlayer but trying to connect to it yields a 'Could not connect to the debugger.' error.
Could it have something to do with using the IL2CPP compiler? In previous versions I used Mono but in the latest version of Unity that stopped working (ARMV7 compiler duplicate symbols etc) so I was forced to switch to IL2CPP...
I'm running latest versions of Unity on both platforms.
The IL2CPP scripting backend in Unity does not support managed code debugging, so this will not work.
You can debug the generated C++ code with Xcode though, here is a place to start:
http://blogs.unity3d.com/2015/05/20/il2cpp-internals-debugging-tips-for-generated-code/