Xcode and the entire stack behind it do not run on Windows or Linux. It would take a team of engineers months to pull it off, then another team to continuously support it. In those months, the feature set of Xcode and the compilers will have improved again and there would never be a stable version for a different platform.
Porting Xcode to Windows or Linux would probably be the worst idea Apple ever made.
Xcode is just the IDE right? No particular need to port that if you can just use Eclipse or the command line tools. The simulator could come later as long as you can test on a device so all your really looking at is a objC compiler and a linker.
Whilst I'm sure it's not a trivial task something tells me that there is more to this than technical limitations.
Along with XCode comes the iOS simulator, debug tools, publishing/packaging and certificate handling. And of course there is more to it: diminishing returns.
Xcode and the entire stack behind it do not run on Windows or Linux. It would take a team of engineers months to pull it off, then another team to continuously support it. In those months, the feature set of Xcode and the compilers will have improved again and there would never be a stable version for a different platform.
Porting Xcode to Windows or Linux would probably be the worst idea Apple ever made.