If you’re trying to work out how to run iOS apps on a Windows PC or laptop, you’ve probably discovered there’s an app called iPadian.
By the developer’s own admission, this is a simulator, not an emulator, so it cannot run iOS apps. It merely gives you a feel for what iOS is like - in case you can’t look at a friend’s iPad or walk into an Apple store - but it doesn’t even do that very well so don’t bother installing it. And certainly don't pay $20 for it.
The simple fact is that there is no emulator for iOS that you can run in Windows, and that’s why you can’t have your favourite iOS app such as iMessage or FaceTime on your PC or laptop. It just isn’t possible.
However, if your reason for wanting to run iOS apps was because you want to play a game or another app which isn’t exclusive to iOS, there might be a solution.
Bluestacks is an Android emulator which runs on Windows and allows you to install and run games and other Android apps, so you might be able to do it that way.
We’ve got a separate tutorial explaining the various ways to get Android apps running in Windows. And although you probably want to run the game on Windows, it's worth remembering that many of the latest Chromebooks run Android apps natively, so no extra software is required.