OSDev.org

Is it possible to just write/port a different OS (possibly Android?) to the iPhone hardware, so you don't have to abide by Apple's interfaces? I know that some people have figured out a way to dual boot Linux on the iPhone, and that it's just a regular ARM with some shiny addons. If you did that, do you think it would violate your service contract?

It's possible, but Apple won't help you do it.. hardware documentation will be hard to come by as well.

Here is an attempt to create a port of Linux, it seems they have a proof of concept boot loader available.

http://www.iphonelinux.org/index.php/Main_Page

Sounds like a challenge .

However, not one I have time for. So I guess I'm adding ARM to my "architectures-to-port-to-once-Khaos/x86-is-done" list. I'll get to that in a year or so... maybe by then well documented Android based smartphones will have taken over the market.

You can use any language the supports the cdecl calling convention with Cocoa/Obj-C. Obj-C IS C, with fluff (essentially smalltalk)
You simply need to initialize and wrap some things (C++ is lovely here) to get it up and kicking.

What you need:

• The library: System/Library/Frameworks/Cocoa.framework/Cocoa
• Call BOOL NSApplicationLoad(void) before using anything else in the framework
• Implement the Obj-C 2.0 Runtime (You likely will only need the sel_* and objc_get* functions to do basic things)
• Learn the object messaging format (Easy peazy)
• Convert the Obj-C function declarations found in the Cocoa frameworks to your language, and have at it.