Can't connect iPhone 6 to AirDrop on iMac
After many wasted hours of trying to do this, I tried online chat with Apple Care who finally diagnosed the problem. For me however it was bad news! They pointed me to below article, and as my iMac is a 2011 model the bluetooth engine is not compatible with iPhone 6. Even worse news is that it cannot be upgraded unless I fork out for a new iMac:
System Requirements
To see if your Mac works with AirDrop, make sure youre in the Finder by clicking the desktop (the background area of your screen), or by clicking the Finder icon in the Dock. Then, check to see if AirDrop is listed as an option in the Go menu. If you don't see AirDrop listed, your Mac doesn't support this feature.
In order to transfer files between a Mac and and an iPhone, iPad or iPod touch, your iOS device needs iOS 7 or later installed and your Mac needs to be a 2012 or later model.
To transfer files between two Mac computers, you need one of the Mac models listed below and OS X Lion or later.
MacBook Pro (Late 2008 or newer)*
MacBook Air (Late 2010 or newer)
MacBook (Late 2008 or newer)*
iMac (Early 2009 or newer)
Mac Mini (Mid 2010 or newer)
Mac Pro (Early 2009 with AirPort Extreme card, or Mid 2010)
*The MacBook Pro (17-Inch Late 2008) and the white MacBook (Late 2008) do not support AirDrop.
For help identifying your Apple product, choose About This Mac from the Apple menu, or refer to the Apple Support website.