Last week I blogged "A New Future For Flex?" in which I said that when Flex 4.5 support for iOS development come in June it will probably work by porting your ActionScript to native iOS code. I was wrong.

Flex will work on all the mobile platforms it supports (Android v2.2+, iOS and Blackberry Playbook) by virtue of the AIR runtime.

In fact, with Flash Builder 4.5, you can already create ActionScript Mobile Projects to run on iOS (iPhone, iPod and iPad). Coming in June is a new release of AIR (and Flash Builder) which lets you create (and port existing) Flex Projects to iOS.

As I understand it, when a user downloads/installs your AIR-based app for their device, if they don't already have AIR on the device, it's downloaded/installed as well in the background?

As a teaser here's a video of a Flex app running on Mac, Windows, Linux, Android, iPod and iPad. As well as in a browser.

Like he says in the video there's no other platform available that can do that!

As is mentioned towards the end of the video there's a separate Flex project for each of the target platforms. However, all the code is stored in one common "library project". As is demonstrated, the code in the iPad project is only 20 lines long.

The author promises to release and open source the code. In the mean time there's another example of targeting multiple platforms for a single app available. It's the Expense tracker application developed for Adobe by a company they paid to make these reference projects. There's also a multi-platform shopping cart app and a sales dashboard. Read more about the three demo app here.

For a simpler demo to get you started building apps for mobile with Flex take a look at the Twitter Trends app. It shows the basics off quite well without worrying about multiple platform considerations.

Hopefully you're as excited as I am by all of this? I'm so excited I've gone and bought a 2nd hand Galaxy Tab off eBay! I tried rooting Karen's old HTC Tattoo to get Android 2.2 on it, but that's a level of geekery I have to admit it a bit beyond me.

Why an Android? It's easier to develop with. Flash Builder can run and debug apps on your Android device over USB. Although I have an iPad already, to run your app on there involves syncing the exported app file to the iPad via iTunes, which sounds a bit too messy for day-to-day development.

Most of what I'm writing here is based on what I've read, rather than on what I've actually done. As I get round to doing some doing I'll keep you updated on what I find.