Since 10.10 and iOS 8, AirDrop is available between Mac OS and iOS if you have a fairly recent Mac (>= 2012 for MacBook Pro) and I don't understand what changed between 2011 and 2012. I know that for older Macs it's a bi-band issue (Why doesn't AirDrop work on older network adapters?) but as AirDrop works between Macs, what's changed in AirDrop with iDevices?