The Software You Need
To begin with developing your iPhone applications, you have to have the appropriate software. XCode IDE is essential for the development. To acquire the XCode IDE, you should become an Apple developer. If you just want to fool around and just test the waters, you can be a developer without cost by registering with Apple. There are several options for you. The free option will assist you to download the recent version of XCode which is 3.5, and you can make use of the simulator that Apple provides and create your own applications. The second option will cost you $99 annually as it will allow you to download the recent XCode preview, which is 4.0, as well as submit your apps to the Apple Store and download your apps to your phone for testing. If you are planning to be doing any type of real developing, I suggest that you pay the $99. However, there is one issue with this method. If you are a sole proprietorship then you must register as an individual. If you are an LLC or any other kind of business, you can use the business development alternative.
You can download XCode when you've got your development membership setup. For the purposes of this site, I'd possibly use the XCode 4.0, as this is the way Apple will be heading in the foreseeable future. You should be able to follow along with XCode 3.5, but using 4.0 will make it easier. My next post will go into the basics of XCode, so make sure that you get ready by downloading it.
The Things You Need To Understand
Here are several other things you need to be familiar with - for starters, iOS. This is Apple's mobile operating system. It is used for iPhone, iPod touch, and iPad. I will have a follow up post that will go into greater detail, but if you want to jump ahead, you may check out several of Apple's documentation.
Objective C is generally employed when developing these applications. Now you can use C and C++, but Objective C is usually used by most. I will dive into this in more detail later on, but if you are interested in attaining a number of information early in advance, I suggest Programming in Objective C 2.0.
Another concept you will need to become familiar with is Cocoa Touch. This is the API that is an advanced interface to the system. It sits on top of the OS and supplies you with access to all the views and user controls and stuff. Again I am going to plunge into this in a later post.
Other Excellent References
In case you are really ambitious and want to get started right away, I advise a few things. First, this is a convenient eBook and crash iPhone development course. This course was extremely helpful when I was ramping up, and the book was solid as well. If you purchase the crash course, the book gets thrown in without cost. Also, if you prefer the book in your hands, the book referred to as iPhone Development was valuable.