In my experience, if you want to view your maps on an iOS device, you can either build a map in ArcGIS.com and then download the free ArcGIS App from the iTunes and view the map on the device. Or you can use Flex 2.5.1 and build a custom app for your iOS device. I have done both and have been pretty happy with custom built app. Just contact me if you want to see a demo of the custom app (froberts at innovateteam.com). Unfortunately, there isn't any simple way to view a flash app on a iOS device(ie the Flexviewer). Of course with enough time, caffeine and money anything might be possible....