Studies show that more than a third of Swiss employees are active on social networks such as Facebook every day during their working hours: how will the weather be tomorrow, what’s the breaking news on 20 Minutes, posting something funny on WhatsApp group chat, an SMS to Mum, how can I get from A to B fastest, pick up some bread & chocolate and “Wow, I have to go there too”.
This entails risks for the employer such as loss of focus and productivity, security risks, loss of time and costs, loss of reputation as well as violation of company and trade secrets. Employers can therefore issue instructions, warnings and ultimately even termination properly, and rarely even without notice, provided that the termination is not an abuse. From a legal point of view, the employee has a contractual obligation to the employer to work carefully, with focus and to the best of their ability. To ensure this, Implenia, for example, has imposed a strict mobile phone ban on its apprentices during working hours.
On the other hand, more and more employers are making smartphones or tablets available to their employees, who can use them for professional and private purposes or pursue a ‘bring your own device’ policy. Employees are encouraged, for example, to network on professional networks such as LinkedIn and XING, receive orders/inquiries by mobile phone, check e-mails or write blog entries and tweets.
The fine line between professional and private use of social media is thus becoming increasingly blurred, which is why clear instructions from the employer on the (private) use of electronic means of communication, e.g. by means of usage regulations, are recommended  https://www.aargauerzeitung.ch/wirtschaft/implenia-greift-durch-handy-verbot-fuer-lehrlinge-auf-dem-bau-131368658.
2] http://www.faz.net/aktuell/beruf-chance/beruf/handy-am-arbeitsplatz-darf-der-chef-smartphones-verbieten-15508148.html;Isabelle Wildhaber and Silvio Hänsenberger, contract law / termination due to use of social media, in: Recht im digitalen Zeitalter, Festgabe Schweizerischer Juristentag 2015 in St. Gallen, 2015, p. 399 ff.