I want to develop an iOS mobile app using Xamarin in Windows. Can Apple Mac OS run on a virtual machine in Windows, rather than run on a separate physical machine as build host?
If possible, any link to the setup would be appreciated, for running Virtualbox, Windows 7, Mac OS.
http://developer.xamarin.com/guides/ios/getting_started/installation/windows/
As stated above, it is not in Apple's terms of agreement to run OSX on anything but an Apple product so you shouldn't do it.
Although if for some educational reason you were to install OS X Yosemite ("Hackintosh" ) inside of Virtual Box on Windows, set the Network adapter to "Bridged Adapter" and get the Xamarin build host installed and running (as well as Xcode from the App Store), then it might be possible to connect from Visual Studios. But as stated, you shouldn't do it ;)
Short answer: Yes it can
Long answer:
As it's been noted in the comments above, you can only legally (wrt license) run a OSX VM on Apple hardware.
IOW if you have a Mac Book Pro (or any Apple hardware) running Windows and a VM running OSX you're fine, both technically and license wise. OTOH you're not fine to use any other (non-Apple) computer brand running Windows and virtualize OSX.
The setup itself will be identical, from Xamarin's tools perpectives (the above linked documents still applies). It will be two computers (one real, one virtual) communicating with each others thru the (virtual) network.
