I am an Indian living in Switzerland since 25 years. I believe I am fully qualified to answer this question.
There are no slums in Switzerland. The social system here is very strong. If you fall into poverty, this social system will kick-in and will not let you reach the poverty level of slums.
You see, the social system will help you but will not let you simply sit and do nothing. You will be offered some job based on your capabilities.
You may find few homeless people in the city center. These people are either drug addicts, alcoholics or have voluntarily chosen that lifestyle because they do not want to work at all. The government still supports them in a very limited way by providing some shelter facilities where they can go and sleep over night. In fact they are expected to pay a small amount of money if they would like to use those facilities.