Every now and then I get mails from people asking if its possible for them to start programming for the iPhone OS on a Windows machine. My first reply is that if they are serious about this – they should just go out and buy the cheapest Mac there is out there for less than $600.
But then, this may be too expensive if you just want to dabble in the environment and see if this is something you want to pursue further. EDUmobile offers a remote mac access facility, which allows you to login to a real Mac using a normal web browser. This can get you started.
Apple is probably never going to release a development environment / SDK that works on a Windows machine – so don’t expect a miracle to happen. 
There are however some illegal ways that you can create a Virtual Mac OS environment on a regular Windows machine and there is the famous “hackintosh” solution – but it is going to probably cost you a lot of productivity time as Apple frequently updates their SDK requiring you to spend time to re-setup things over and over again. I won’t tell you the details and I don’t really encourage this, but it is possible if you are very short changed and if you are desperate. Do note that you will need to eventually buy a Mac when you get to the point of wanting to publish your game as you need a valid machine hardware footprint for that. This is just a stop gap option for you.
So, the truth is that there is no real iPhone SDK that runs on Windows environment – despite what many software vendors may tell you. However – there are some ways for you to develop your iPhone app in Windows.
You can get a bit clever in developing on these environments and then when you are ready to compile you can access a remote Mac like that offered by EDUmobile.
Here are two iPhone development game engines (both offer free trials). Both of them can compile into code that is native to the iPhone. Many apps available in the iPhone App Store have been created with them.
- Unity3D – This game development engine and editor utilizes Boo and C#. The editor works on both Windows and Mac.
- Stonetrip S3D – This game development engine and editor utilizes LUA. The editor can run inside Windows.
The following next two solutions allow you to create apps using web technologies like HTML, CSS and Javascript. You can then run them through an Objective-C framework that responds to actions within a UIWebView. This allows you to access native functionality on the iPhone. Both there frameworks are free.
- Appcelerator Titanium – This is the most complete of the development platforms that are currently available, not counting the two game engines above. Extensive support is provided.
- Genuitec MobiOne – This tool is basically an interface designer. It uses the Phonegap framework to deliver native functionality and it runs only on windows.
There are two other other solutions that are in testing and may require upfront payment without any form of trial. They are:
- Flash CS5 – They say you can altogether bypass the Mac with this.
- Dragonfire SDK – Visit the site to sign up for Beta version.
UPDATE:
A new entry to this list is MobiOne. It has indeed come a long way since it was first released with a lot of improvements and new features have been added. It is very easy to use, and you can build your app with the built in drag-n-drop functionality, and test it quickly. It allows you to develop HTML and Javascript based apps from within their IDE. Grab it from this link – http://www.genuitec.com/mobile/ .
Watch a video demo of a recent version of MobiOne below –