See https://github.com/iotile/iotile-mobile-ionic/issues/804 for significant discussion but basically, phones default to rather slow connection intervals and the peripheral needs to request faster ones if it wants. However, the rules for each platform are slightly different in terms of what they will accept so we use a platform dependent strategy to hopefully narrow in on the best interval.

In particular, android appears to always pick the highest value in your range and iOS only really allows you pick 15 ms or 30 ms and then sometimes still just gives you 30 ms.

Test Results:

• Moto X 2nd Gen (Android 5): Rejects [7.5, 10], accepts [7.5, 15] at 15 ms. Requires a delay between updating the parameter and querying it for the change to take effect.