TL/DR: Any sport (and swimming is an excellent one) will work, if done consistently, with applied hard effort and together with healthy diet and caloric deficit. No way to do it without clear goals and determination.

To burn 1kg of body fat, you need to get a deficit of 7000kcal (actually 1kg of pure fat has 9000kcal but the body stores water and other tissue to support the stored fat, so if you lose 1kg pure fat, you would have lost more body weight). Caloric deficit can be achieved by consuming less food (less calories in) and being more active (more calories out), preferably both at the same time. Eating healthy, calorie-sparse unprocessed foods makes it easier to manage appetite. Those foods are nutrient dense and fulfil your body needs unlike heavily processed thus named "junk" foods. And working out harder makes your body burn more energy and build/maintain muscle - the tissue you need to keep burning fat. 

And actually swimming is much better than jogging for fat-burn - it burns more calories and allows to make more intense workouts (bursts or fast freestyle swimming) without straining joints or spine. The key to be taken is that any activity that helps burn substantial amounts of energy will do. But even if you work out a lot, it's very easy to out-eat the benefits of physical exercise. One hour of continuous swimming will burn 700-800kcal. One pizza is between 1000 and 2000kcal. Sport and healthy, calorie-conscious diet should be used together. 

But weight loss is result of long-term habits. This is slow (yet, very rewarding) process. There is no quick-fix, there is no diet or pill that can do this without hard effort and determination. It requires huge amounts of long-term motivation to stay focused on your goal. The goal of losing around 80kg of body weight is achievable within about 2 years of hard work. In my experience coaching people, the motivation to change yourself usually comes from break-ups, ultimatums, sometimes as attempt to get out of long term depression, new-found health problems or other sources of personal epiphany. But I have never seen it work if the person doesn't really want it and is doing it for someone else.

Edit: One book that I read and really helped me was "Burn the Fat, Feed the Muscle" by Tom Venuto. I really liked it because it emphasised not on specific foods or routines but how to set goals, measure progress and change your mentality towards a consistent healthy lifestyle. It thought me that there are no shortcuts but that you could look the way you dream, not the way you believe it's possible. Hard work and consistency is the only way but once you change your mentality it gets much easier. It also explained macronutrients and how to make smarter food choices.