We are also interested on this topic. We just tried to connect RS2 with iOS bluetooth without success. So I assume, the devices are still not trusted?
There is a number of cities that are restricted to iOS mobile devices due to IT security policies (let’s not discuss wether this is a good idea, we just have to face this fact). As far as I have found ArcGIS collector does not support TCP-data stream, therefore this workaround does not help in this case.
We have introduced RX MFi (RX should have the MFi mark on the unit’s bottom), which supports connection on iOS devices using Bluetooth. Here’s our ArcGIS Field Maps integration guide.