+1  A: 

C/C++ is a good start.

Mac Desktop development would also be a good background considering it's the only other widespread use of Objective-C.

C# is ok, but isn't directly related to the iPhone (unless, of course, your client is ok with you developing the app in MonoTouch).

Other development for mobile platforms would definitely be another plus. It shows that you have the experience at dealing with issues that you'd only find in the mobile space. If those mobile applications where for touch-screen devices, that's yet another bonus.

Personally, above all else, I'd be doing my best at showing my ability to adapt to change quickly, learn new things, and be instantly able to apply them.

Justin Niessner
Poor u, but MonoTouch is banned :)
vodkhang
@vodkhang - In theory, yes. In practice, Apple is still approving MonoTouch applications (even ones that utilize the iOS 4 features).
Justin Niessner
A: 

C is a good background, sure. Because you will also have to deal with manual memory management, pointer.

OOP will also a good background (you have C++ which is equivalent)

Mobile can be considered a background when you know the major problems with mobile, like memory, performance, small screen.

GUI-development: it depends on the level of designing and usability you have because IPhone requires some higher level to think about UI

vodkhang
A: 

iPhone development is new to most people, don't hesitate. ObjC is a wrapper on C, and very close to C++. Any knowledge in Java, C# would be great.

If you are coming from a .Net environment, you might need sometime to get used to XCode and ObjC.

medopal
A: 

You mention that you have C# experience.

Check out MonoTouch which allows you to develop your iPhone / iPad applications using .Net and then convert the code into iPhone XCode automatically.

Brian Scott
I don't think that's an option :-(
Olav
A: 

I was coming from .Net/ C# and in my opinion, the language is not that big problem, especially when you start developing. Also xCode is okay, although when you come from Visual Studio it doesn't feel good. But one can get used to everything :-)

One thing you should always have to remember is the memory management and the whole pointer / call-by-reference stuff.

The most time consuming thing is to get to know the framework and all the (ui)concepts from the SDK. You will need some time to figure out all the cool stuff from objective-C, but if you start with a project not that huge, I think you will be fine.

If you already have developing experience, a good book is "Advanced iPhone projects".

dalind