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My First iPhone App

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What do I need to Start Developing for iPhone?
Finder Screen showing Xcode.app
You will need these for this tutorial:
  • A Mac Computer running Mac OS X 10.5 or higher
  • Free Membership of the Apple Developers Group
You don't need an iPhone to start with. Xcode, the free development system that you download from Apple includes an iPhone emulator. The emulator is excellent and will take you 90% of the way there but you can't use it for hardware functions such as GPS, the accelerometers or accurate timing. For the last 10% you will also need
  • An iPhone 3G or 3GS, an iPod Touch or an iPad
  • An annual $99 subscription to Apple developers so you can run your app on your iPhone/iPod Touch/iPad and release to the App Store.

You cannot run your apps on your iPhone unless you've paid $99. In the basic tutorials, I won't cover the last 10% so you only need a Mac and free membership for them. I use a Mac Mini for writing this.

Paid subscriptions provide access to the beta versions and older versions. The 3.2 SDk (for the iPad) is currently up to beta 5 as I'm writing this.

Public Key Encryption

Unlike with Windows, Linux or Mac OS X where anyone can write and run an application, to run an app on an iPhone, it must be approved by Apple. That's true even to run an application on your own iPhone, but that approval is automatic if you've paid your annual $99 fee. To be distributed through the App Store requires you to comply with a series of rules and have a payment agreement setup with Apple. These rules aren't particularly bad but get one wrong and you'll be set back a week or two and need to resubmit. The average approval time is under 5 days and with over 140,000 apps, clearly it works.

To run your application on your iPhone you must generate a Digital Certificate. This is basically just a very big number that is impossible to generate (at least using present technology) in any other way. Your application is digitally signed; a special checksum that is generated from your application and your personal Apple approved developer information. This is then used in conjunction with your iPhone and a digital certificate produced. Your iPhone will only allow you to install applications that have compatible certificates.

The Xcode development system provides all the tools for generating and manipulating digital certificates and is free. It's not rocket science just a little onerous having to do these extra steps! We'll get started on the next page creating an Xcode project, so you'll need to download Xcode from Apple and open the dmg file to install it first. After that you can find Xcode.app in the Finder under

Developer/Applications/Xcode.app

On the next page Creating an Xcode project
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