Beacon ranging is far more accurate in Estimote app than my app

When ranging for beacons in my app, the array of beacons sent to didRangeBeacons is very jumpy and unstable regarding which beacon is the nearest. I have one beacon right next to my phone, and another placed 3 meters away.

When opening the Estimote app, and listing the beacons nearby, the listing there is totally stable, always showing the nearest beacon correct.

Is the source code of the Estimote iOS app available somewhere, so that one can see how it`s done there?

I am starting ranging of a region specified with only UUID when the view appears. didRangeBeacons is called once every second with the list of beacons, but the nearest one in the list is often not the physically nearest one. I know that the accuracy is not 100%, but it is strange that the Estimote app is getting it correct, then.