I can't seem to find the right documentation, tutorial or SO post to point me towards the right implementation so far... even though there are many posts about this topic floating around.
Problem
I have an app that connects (pairs) to a BT device I built. What I want, is when the user presses the home button or backgrounds the app I want to send an update through a BT service layer to a BT device on a regular interval. I am doing this now (only fires once) in the applicationWillResignActive and applicationDidEnterBackground methods and it works perfectly. The problem is that I can only perform this once it seems. Any loops, timers, background type services that I start up in these methods, die very soon there after.
What I need
Is for the application to keep looking for my BT device in the background and every 10 seconds or so and send an update to the device. I first need to check to make sure the app is still backgrounded, but once I know its in the background I wanna send the update. When the app comes back in focus I can stop the updates to the BT device but its crucial that it sends them when the app is not in focus.
Research
I have found these SO posts (long-running tasks, background task execution handler, using this in an NSTimer loop... but it dies) but they have not helped with implementation at all.
When I wrote this post I was far too new to OBJ-C and didn't quite understand the concept of delegate methods with the proper access level to fire in the background (i.e. info.plist access under bluetooth-central).
The end result a month later was to build a peripheral device that could wake up the application in a timed loop via subscribed characteristic updates. Once the app wakes up, you have 10 seconds to handle the event that has just occurred and since I am only saving off a copy of the data that the device posted, all is well.