How to see compass accuracy and recalibrate the compass in iOS 10? My compass is often wrong, which leads to all directional modes of maps being wrong (very annoying for back country trail following).   In old versions of iOS I remember the 'figure 8' popping up sometimes, but you don't see that anymore, nor have I found a way to determine if my compass is calibrated or not, other than checking the width of the blue cone in the Apple Maps app when you are in compass mode (it seems to get narrower as the compass is more accurate).

Is there any way to force recalibration in iOS 10, and/or see further information about current accuracy?
In troubleshooting this, I learned a few important things:


While there is no way to manually force a recalibration of the compass aside from toggling location services on and off, generally the compass attempts to recalibrate itself when an app requests it if it has not been in use.
The 'blue cone' in maps seems to be the best way to easily tell how accurate the calibration things it is.
Arguably most importantly (and most embarrassingly), my issues were entirely caused by a case that I was using that had a small magnetic clasp in it.  Everything worked just great after getting rid of it.