Several users contacted me reporting not to be able to log in to the Groundspeak API from within iCaching.
I started an investigation, but even an older version of iCaching (that did work for sure previously) cannot log in any more. So it was not a code change on iCachings side that broke the login.
Currently I’m in contact with Groundspeak to solve this problem.
Excuse for the inconvenience.
Update June 17, 2016
The friends at Groundspeak were able to figure out that the issue is related to login and user language. They are working on a fix.
In the meantime there is a workaround: temporarily change your user language in your Geocaching account to English. Then login in iCaching and after that you can change your language back to whatever you want.