How it all works
We enabled this by using the Low Level Virtual Machine (LLVM) compiler infrastructure. LLVM is a modular, flexible compiler system that is used widely in a variety of projects. The key reason we choose LLVM is its flexibility and applicability to iPhone development.
We created a new compiler front end that allowed LLVM to understand ActionScript 3 and used its existing ARM back end to output native ARM assembly code. We call this Ahead of Time (AOT) compilation—in contrast to the way Adobe Flash Player and Adobe AIR function on the desktop using Just in Time (JIT) compilation. Since we are able to compile ActionScript to ARM ahead of time, the application gets all the performance benefits that the JIT would offer and the license compliance of not requiring a runtime in the final application.
By doing the compilation step, we allow developers to create applications using their Flash skills and their knowledge of ActionScript 3. In the process, we also expose the APIs that developers are familiar with so they can not only use the ActionScript language but follow the customary app-building model. When you build your application for the iPhone, there is no interpreted code and no runtime in your final binary. Your application is truly a native iPhone app.
http://www.adobe.com/devnet/logged_in/a ... phone.html
