A German Uni's (Darmstadt) IT mob developed an app called AirGuard that has been doing tracking device monitoring for some years now. I have it running right now.
Why on earth re-invent the wheel? A bunch of clever folk have been doing this for years.
I can't find an Apple version so I might suppose that either Apple's nose is out of joint with regards the name, or an Apple version was never released 8)
In the end this is a very decent resource and it should have been covered off by phone floggers, years ago. It's rubbish that G and A are presenting this as something new that they have come up with.
Why on earth re-invent the wheel? A bunch of clever folk have been doing this for years.