@jcaron, ah, that is a shame - but thank you for letting me know. I was hoping this could be done passively, without having to build an iOS app.
Basically, I am trying to get the Pycom board to search through the advertising BLE devices on startup to determine if a specific one, my phone in this case, is present or not. Then the board will take one of two actions depending on if the phone is present or not.
In standard Bluetooth, there is the process of pairing, where two devices can in effect remember each other. I was hoping there would be an equivalent for BLE.