YOU CAN DEVELOP IPHONE APPS ON WINDOWS PC. I've done it, with complex apps. And it works perfectly. You can develop iphone apps without ever seeing a mac or iphone.
You can develop on windows an HTML (or better: HTML5) app, using tools like Sencha or JQTouch, or mobi1. (They used to all be free for a while)
Then you use openSSL to sign the app. And Adobe PhoneGAP Build service to build IPhone App.
But you need the iphone developer licence to install it on an iphone. But you don't need a mac or iphone at any minute to compile, build or test it - all that is done ON THE PC.
I've done it, and it works perfectly. (But with Android type responsiveness - not as fast as a native IPhone app)
You could also use a program from the the Babylonian era (circa 300 bc) running C and C++ called dragonfly. If your app has one or two screens with limited interactivity, and many calculations, go for it. It includes an emulator. You compile to the iphone at the press of a button. (Not sure, but I think you do need a developers license in any case)
And then there is Xamarin. You develop in C# with special calls to native code. You'll have to learn the environment.