Do I need a Schengen visa?

My nationality Obligation to hold a visa (yes/no)
Iran  Yes (V) (M:D)

(V)
You are exempt from visa requirements if you are in possession of both a valid residence permit issued by a Schengen member State or a valid type D visa and a recognized travel document.

(M:D)
You are exempt from visa requirements if you are holder of a diplomatic passport and wish to enter into Switzerland: on an official mission or for other travel purposes without exercising a gainful occupation. 

Other nationalities

For other nationalities, please refer to the list on the webpage of the State Secretariat for Migration (SEM).

SEM – Overview of ID and visa provisions according to the nationality (Annex 1, List 1: nationality)

If you are obliged to hold a visa, please apply for it and refer to the information on the webpage:

Where to apply for a Schengen visa?

If you are not obliged to hold a visa, you are allowed to enter Switzerland resp. the Schengen territory and stay up to 90 days within a 180-day period without any visa.