I would like to get notified when ios app is in range of other ios app even if they are both in the background mode. I know that I cannot advertise successully as a ibeacon after my ios app has gone to background because advertisement data is put in 'overflow' area. But the question is if we can extend the time that it is possible to advertise/simulate iBeacon? Are there any workarounds for this?
For example can I connect the devices in range by knowing their proximity UUID without user even knowing it? That would allow me exchange data between devices because my plan is that every user device will advertise with the same proximity UUID and the way I will identify users will be mix of major and minor ids.
Thanks in advance!
While iOS devices may not advertise iBeacon in the background, they can advertise what is known as the Overflow Area advertisement, which contains 128 bits of data. These Overflow Area advertisements are readable by backgrounded apps on other iPhones in the vicinity, provided those iPhones have their screen illuminated. (This happens even when phones are unused, as screens are typically illuminated briefly after a notification comes in.)
This makes it possible for one backgrounded iPhone app to read another backgrounded iPhone app's unique identifier passively in the background with no user interaction.
Advanced techniques are needed to configure Overflow Area advertisements, and to encode/decode unique identifiers inside them. Fortunately, I wrote up a detailed blog post of how this works, and created an open-source reference app you can use as a starting point to building your own app. This way, you don't need to master the complexities yourself to get this working.
If you build and run the reference app on two iPhones, it will assign a unique numeric identifier to each phone, and then you will see that Phone A detects the unique identifier of phone B and vice versa.