Developing Iphone and IPad applications is supported only if it is developed on a Mac. This is especially true if you want your application to end up in the App-store. A good explanation is given on another stackoverflow site here which ties together your Objective-C question and writing for the IPad.

Apple, unusually perhaps, have an excellent IDE and development tools which they give away for free.

I would either buy a used Mac, or (if you have a license) - install a virtualised OS-X in VMWare etc.

KDevelop does have some Objective C patches - but it doesnt look like it is actively supported.