how safe are capetown and Juhansburg for opening a restuarant?

Dears.
As I intend to go to capetown and join and staying to the english school for 3 month I want to know how safe is the capetown?of course i have been in some part of africa several time ,and it will be a new expreince to stay there.my main point to go there opening a kind of meditrainian snack bar offers differnt kind of kebabs(roast meat-chiken-fish).however will be very glad to inform me about this kind of business in capetown.
which city is better for this business,capetown or juhansburg?
waiting to hear you soon.reza