How much of the local language do you need for daily living? Are local language classes/tutors available and affordable?
At least a bit of German would be quite helpful. The Zurich variant of Swiss-German is exceptionally difficult to understand, so abandon all hopes to learn German while you're here. - May 2016
Pretty much everyone here speaks English (or to a certain extent.) So don't kill yourself learning German. Plus, this city is tricky to learn High German because the locals speak Swiss German and if you try to talk to them they will speak back to you in Swiss German! - Aug 2014