How much of an iPhone app can be developed and tested on Linux?

I develop some iPhone apps for clients, but I prefer working on a Linux machine. I know that there are certain things you need to do on a machine running OS X, like build the final distribution, run the iPhone app in the simulator, etc.

But I was wonder how much of say, the model layer, of an iPhone app you could build and test on a Linux system using plain Objective C and various libraries copied over from the XCode Developer libraries. To w开发者_Python百科hat extent is this feasible?

I don't want to jailbreak an iPhone to do this.

How much of the Foundation API can you run via GNUStep?

This seems to be give a good answer: Starting iPhone app development in Linux?, which provides a link to http://www.saurik.com/id/4. In theory, it's using gcc4, but the entire toolchain is a difficult replacement. But if you're really intent on doing this, it looks like at least some of it possible in Linux.

Well, there is GNUStep. A domain model and unit tests wouldn't be a problem at all. Creating some of the artwork could be done in Inkscape, which probably runs better on Linux than a Mac.