If you want to develop an app on a windows box the only real options you have is possibly using https://xamarin.com (c# development for iphone)

If you already have an app and just want to build/deploy/test .. you may want to look at renting a Mac from the cloud. You can remote to it from a Windows box:
MacinCloud - Rent a Mac in the Cloud! - Mac in Cloud

Hope this helps!

-Tom

Programming in Windows for iOS Apps ?

The first thing you need to do is plan your app and decide what features you need in your App. so that you can select the best framework for you App.Choose a framework that uses the languages you prefer , Many of the frameworks offer a free trial, so test them before you buy .

Some of the more popular frameworks are:

Appcelerator: Use XML, CSS-like code, JavaScript

Xamarin: Code in C# or .NET

Adobe Air: Use Flash, Dreamweaver, JavaScript

Marmalade: Code in C++. Gives the option to develop in Visual Studio or Xcode

Unity: Use a GUI to design your app. Unity focuses on game development and can deploy to mobile and game consoles

PhoneGap: Code in CSS, HTML, or JavaScript

One big problem with trying to do it entirely on Windows is what happens when it's time to distribute your app: Apple has a number of hoops you need to jump through (you need to get a developer certificate, then one for your company, then register your test devices, etc.), and XCode makes that process 10x faster than trying to do it all by hand on developer.apple.com.

A while back I tried to make it work by using an OSX virtual machine on VMWare, but while I was able to get the code compiling it was endlessly frustrating trying to test it--I couldn't get an iPad to sync with the virtual machine. I ended up buying a refurbished Mac Mini on eBay, which I should have done in the first place.

So, I second the MacInCloud suggestion if you're doing a modest amount of work and suggest getting a dedicated mini or laptop if you're doing something more substantial.

I have heard of some guys that were able to boot a hackintosh, (but all in all, your going to spend way more time fighting with it than being productive.) MAC in cloud is a good method of trying it all out, (but you do need a decent internet connection) (also be sure to go over the videos, it will save you some time)

If you get the workflow process down you can pay by access and still manage to save some money, but if you plan on spending any amount of significant time working on a MAC get one, (they are affordable on ebay, but watch out for the fine print, )

you can use a virtual mac, and use xcode, or even buy time on a remote mac.

that is the most straightforward way, to use Xcode, unless you want to use third party sdks like unity, xamarin, etc...