How hard is it to learn Objective-C for iPhone Apps if you know C++, C and Python already? Is it better to use that rather than just C++ code when writing Apps? If so, why? I want to start iPhone Development and recently got an iMac for my Birthday. How long should it take me to be able to write iPhone Apps in Objective-C? Also, does the SDK cost money, and do you need an iPhone to develop Apps for it?

I can hardly answer most of your questions as I never did any development for iPhone. However SDK is free check iPhone Dev Center(you only need to register with Apple, so they can send you spam) and for start you do not need device as SDK is coming with emulator that should be sufficient. As for learning curve you can check this

I think I heard that you have to sign up to the Apple Developer network to be able to distribute your apps. A good place to start is
This is a windows C++ library. Two things you already have!

OMG thanks! I was going to buy it soon, but I've put in for a spare serial...thanks muchly!

Objective C is quite different from C/C++ . It has lots and lots of quirks and it takes some time to get a grip on the whole thing

I am not trying to discourage you but just sharing my personal experience with you

Objective C is good and easy to learn.
All u need id SDK. you cant learn anything without doing , so u need a Mac and sdk in it.

First you should have a good idea about Objective C. So go though
1. Programming in Objective-C 2.0 by Stephen G. Kochan

To develop small application dont need to study the entire concept of objective C.

To develop go thru the following books
1. Beginning iPhone Development by Dev Mark| Jeff La Marche (Excellent)
2. or go thru Head First or some similar books.

All the Best

To develop and distribute apps for the iPhone you have to pay Apple $99 to join as an 'iPhone Development Member.' With that you get access to support forums, distribution, etc... You don't HAVE to have an iPhone to develop iPhone apps, because XCode has an iPhone 'simulator' that will load your app through a simulation iPhone's interface so you can see how it works. You should know that there ARE different behaviors for some things between running your app in the simulator or running it on an iPhone.