Are builtin 3D arrays and generics okay on iPhone?

I can't seem to find a definitive answer on either of these when I google and look on other forums. Some sites seemed to be saying that 2D arrays [,] were okay but 3D [,,] would crash on the device (but compile and run in the editor). I could make a wrapper class for MultiDimArrays, but it would be good to know if I'm doing it to extend native capabilities or to work around native limits.

Same thing for Generics... this forum thread has a post saying there are no generics on iPhone but it's quite an old thread so I don't know if it's still the case.