Airdrop is not currently working on my Mac when trying to connect to an iOS device.
Here's my experience: Airdrop was working fine around late Nov to early Dec of 2015, then it just stopped working when connecting to iOS device (at first, my parents' iPads). I tried some remedies by deleting the bluetooth plist. It worked again, but just momentarily then it went out again. Tried some on/off toggles in the firewall settings, but did not worked. I went to a nearby Apple store and tried if I can connect to their device; my Mac connected to the Apple store's Mac easily, but when I got home and tried again, it did not work on the iPads. After some time, I just turned our wi-fi router on and off, toggled the firewall settings on/off again, tick/untick the "block all incoming..." in the firewall settings, then my Mac suddenly recognized all of the iOS devices (my iPhone 5C and my parents' iPads) on Dec 25, 2015. It was working great, but then came Jan 2, 2016 when it stopped working again.
Today, Jan 3, 2016, I went to another Apple store and told my issue on Airdrop. The Mac of that Apple store recognized my Mac and mine to the store's, but did not recognize my iPhone. The Mac of the store os an old model, but still recognized my Mac and vice versa. The Apple store's service center was closed because it's Sunday so I'll be returning within the week for some clarifications.
Please note that both bluetooth and wi-fi connectivity works fine on my Mac; my iPhone can sync thru wi-fi, can connect via bluetooth hotspot, can connect via wi-fi hotspot, internet connectivity is good, bluetooth gamepad is recognized and working, transfer of data from different kind of phone thru bluetooth is possible, and older Mac models are recognized.
*Macbook Air 13", mid-2013, El Capitan 10.11.2
*iPhone 5C, iOS 9.2
*Airdrop set to be visible to 'Everyone' in both device