Yes, there are dialects. Written German is "Hochdeutsch" which is spoken particularly in the north of Germany. Then there are dialects within Germany itself which you can most commonly find in German states such as Saxony and Bavaria. The same goes for Switzerland and Austria. I speak "Hochdeutsch" and I can understand most of what people say who speak in dialects but it's difficult from time to time for me as well.

Swiss German is a different language. Here and then I understand a word, no way I can get what they talk. Lets make it worse: Swiss German isn't ONE language. There are many regional differences within Switzerland and I've been told that even CH locals struggle with understanding the language from other regions.

Here's a video of various German dialects and other Germanic languages that includes Swiss German, so you can judge for yourself: https://www.youtube.com/watch?v=T8LxRfdLrlU