If an iBeacon starts emitting (100ms), how long should it takes before a locked iPhone detects it? Let's say the iPhone is very close to the emitting iBeacon but my app is not even running in the background.
In other words, what is the LBE scanning frequency when an iPhone is locked?
On
The documentation doesn't seem to be really specific about the scanning times, and I feel like most of the information one can find is going to be anecdotal.
From my personal research and experience, beacon scanning when the app is backgrounded or inactive is variable on the iPhone's battery level and various other factors. For the most part, in most cases, I've determined that region detection should occur within a few seconds.
With that said, I've noticed that it happens a little faster when the phone is in use, taken out of the pocket, etc. This could be due to the fact that as the phone is moving, scanning is increased to bring the user up to speed and prepare apps for use.
We have done a lot of research on this subject at Radius Networks. The answers are complicated, but the executive summary is that their are two tiers of detection:
Hardware Accelerated: The first beacon apps to register the first 30 beacon regions on the phone get hardware accelerated detection. Thisey get background detection within 5 seconds about 90% of the time.
Software Scanned: Subsequently registered beacon regions get detections as software allows. If no other apps are ranging, this is on a fixed 15 minute interval. Statistics say that the average detection time would be 7.5 minutes for these regions. The maximum time is 15 minutes.
Unfortunately, there is no known way to tell which tier your app will get. Plan accordingly.
Read more here:
http://developer.radiusnetworks.com/2015/04/21/max-beacon-regions-ios.html
http://developer.radiusnetworks.com/2014/03/12/ios7-1-background-detection-times.html