There are different companies offering roof racks and roof boxes. You could check them out online and read a few reviews before making a purchase.Of course, you can install roof racks to a Maruti Suzuki Swift like any other car but most people prefer not to do it unless it is completely unavoidable. The first reason is that it spoils the aesthetics of the car and then the dynamics of the drive get changed with the wind trying to brush past the luggage when it hits speeds higher than 100kmph.
If you are a person who goes for road trips a lot with a lot of stuff to be carried along then perhaps a roof rack is a worthwhile consideration freeing up a lot of space inside the car for a more comfortable drive.
You can also go for the boxes that are available these days that can be installed on the roof of your car. You can be assured that you won't have to tie your luggage if you install the boxes and you also won't unknowingly lose a bag that might have been loosely tied.
I am not very well aware of the types of roof racks available, so if anyone else could help with that, it would be great!