Hi All,
I'm not sure this is entirely solved yet but just wanna share what I have encountered with the OBD II BlueTooth & Wifi hardware devices.
There are quite a few hardware brands/makes out there you can get, some are cheap, some are costly but definitely works. I bought two different OBD II hardware units, ScanTool OBDLink MX Wifi version and the GoPoint BT1A (Bluetooth). Both works very well with it's own free software provided via iTunes App Store. I have no issues connecting via BlueTooth with both iOS (iPad Mini 2, iPhone 5S & iPhone 6+) and Android (Samsung Note Edge, Sony Xperia X2/3) for the GoPoint BT1A unit though I had problems with the cheaper HH OBD Advanced (OEM) product which iPhone fails to detect it but not for Android phones. There's another OBD II unit, "Automatic", it works well if you are in the US, else where does work due to VIN number.
On the software side of things, I personally use Palmer's DashCommand, ScanTool OBDLink (For MX Wifi unit) and GoPoint BT1 (For GoPoint BT1A unit). To date, I prefer to use DashCommand as it has quite a vast tracking results and able to log them down as well. Setting up Wifi requires manual setup but it works. I have other software like Dynolicious, Harry's LapTimer, Speed Tracker recently purchased, NovaScan which I have not tried much yet because some of these are more suited for Tracks which I have not come around to it yet with my AMG car.
Hope that helps in general for some of you.
Thanks.
David