I found this guide below from the Alpine Club, it seems to boil down to common sense stuff really, there are only two places were it's forbidden to camp, Obwald and federal nature reserves and, obviously, the usual list of cultivated fields and the likes but judging by the pictures, if you are in the wildnerness, no one will bother you. It's always a good idea to ask a local farmer if he/she is ok and buy some local products too...

http://www.sac-cas.ch/uploads/media/...biwakieren.pdf

http://www.sac-cas.ch/uploads/media/..._et_camper.pdf