When I tried converting an already existing project (which was built for Flash), I got an Xcode project (with no complaints from MMF2) but when opening it in Xcode it causes Xcode to crash on startup.
I believe this must be caused by some extensions not being supported on the iphone platform, I will look into this and verify it. But MMF2 should give an error and fail to build if unsupported extensions are detected and they should be listed so that we can remove them.