I can not buy one iMac machine and I really really want to learn this fast. Office environment does not allow me to learn and focus is to deliver something quick.
That made me to hunt down ways to learn coding objective-c on windows. There were annoying links and suggestions. Honestly none is perfect and all hacks are just hacks. If you are serious you need to have one iMac machine.
In case just you want to warm your hands quickly, you can try below links.
I was able to write quick hello world program through notepad++ editor. Problem is that I needed to run make each time I had to compile program. Its pain in the butt.
I thought Microsoft WinObjC will help but focus is more of porting or moving the objective-c herd over windows or C#.
This tutorial is handy for novice.
I can update this once I get more dirty.