We are developing an app which connects to a BLE peripheral in the background whenever it gets close to it. What we have used so far is that we monitor a circular region. When the phone enters the region the app will start scanning for peripherals and when it discovers the peripheral it connects to it.
This worked pretty well for the last few iOS versions, perhaps iOS 14-16. It wasn't perfect but for the most part it would feel like it connected rather quickly when you would approach the BLE peripheral. If you listen to music via BLE or talk to someone using your BLE headset then it could sometimes work noticeably worse. But, as said, for the most part it would work satisfactory.
Starting with iOS 17 and analyzing the functionality over the past 6 months or so we've noticed a clear worsening of it. It does generally connect to the peripheral but the user might often have to wait for quite some time. Rather frequently the user must even light up the screen of the phone before anything even happens. It appears that some sort of resource allocation, battery saving feature or similar has affected this functionality greatly. The time difference between entering a region and physically approaching the device is generally around 2-3 minutes.
We have tried to do it more in line with documentation and follow the guidelines that we find in:
So in doing this we do not start scanning for peripherals when a region is entered, but instead we directly invoke connectPeripheral:options:. This way we offload to the system that we want to connect to that peripheral. However, when testing this we see no real improvement. Sometimes it connects satisfactorily. Sometimes it doesn't really connect at all. Many times it connects if the user lights up the screen. So just looking at what the user is experiencing our analysis is that doing it this way works even worse than what we previously did.
I understand that the system has many resources to consider and that some may have to wait while others perform things. But are there any documentation on what one could expect from initiating a connectPeripheral:options: from the background? In the link I posted it simply states the iOS device will reconnect when the user returns home. So not much detail in terms of performance which is crucial for our application.
If there aren't any further details on the performance, are there any other ways to improve this functionality? We are not looking at draining the battery whatsoever but we simply need our background running app to be as responsive as possible for a few minutes after it has been launched by the region monitoring. We understand that battery life is important but since this happens rarely and sparsely (not more than a few times per day) it seems reasonable that there should be a way to be able to make it function properly.
