Hi,
LiveCycle forms do not work on Apple's iOS devices (iPhone or iPad). See http://assurehsc.ie/blog/index.php/2010/05/xfa-forms-in-iphone-and-ipad/
A static form will open, but the user cannot interact with it. A dynamic XML form just will not open.
Forms worked perfectly on a Mac, provided the user opens the form in Adobe Reader and NOT the preinstalled viewer Apple Preview. Several threads on Apple Preview on this forum.
Niall