You can get the (release) iOS SDK for free, but can only run your code in the simulator. When you pony up $99, Apple will sign your code-signing certificate so

You can get the (release) iOS SDK for free, but can only run your code in the simulator. When you pony up $99, Apple will sign your code-signing certificate so that your code can run on unmodified devices, and they will also allow you to submit apps to the App Store.