I love stories like this and one of the reasons why I love the Mac and iOS so much. So much attention to the small details. They didn’t just worry about moving needles…they worried about stuff like (list from the article itself):
* Adding a table of dB values to angles describing the meter’s layout
* Using some math to interpolate between table values and sweep a log scale
* Writing test code to confirm motion and reference marks
* Adjusting sampling frequency and animation speeds
* Offsetting the dB values by that tricky 4dB in the standard
* And verifying against other meters I could find in audio software.
After years of experience of working on Mac audio apps these guys also knew that people would pay attention to this stuff.