How is to get the wall by public transports from Swissotel Beijing? I prefer using subway or train.

Yustina, which part of the wall are you going to visit? If you prefer to visit by train, then I think you should go to Badaling. It's very convenient from your hotel to reach the wall. Please walk from your hotel to reach the Entrance C of subway line 2, take subway line 2 to get off at Xizhimen. Please get out of Exit A1 and then walk to Beijing North Railway Station. There you can take S2 train to reach the wall. It takes around 1 hour and 10 minutes.