Except for the MX charting controls and the MX Spacer control, mobile applications do not support the MX component set defined in the mx.* packages.
So, when I try to compile my MX control heavy application as a Flex Mobile application, I get a stack of compilation "library not found" errors. Yet, when I try to use adt to compile the project for iOS, it compiles (and runs) just fine.
What's going on? What should I be using?
It's not that the MX controls can't be cross compiled for iOS, they can, the issue is that the mx controls are not very optimized for mobile devices, and so are not included by default in a mobile project. You are welcome to link in any additional libraries you want (including the mx controls), even if they are not recommended for mobile use.