Sport Is Life allows you to track your swimming workouts. To do this, in the first version of the App you will have to manually enter all the heats you do, with their distance and time. You will also be able to add a comment to the workout.
In future versions, you will be able to follow your training with your sports smartwatch (which is certified for swimming with it on) and upload your times to Sport Is Life.
Under no circumstances can you swim with your mobile phone. There are smartphones that can get wet with water, but in these cases they always refer to splashing or accidentally dropping the phone in the water and quickly pulling it out of the water, but they never refer to smartphones being in the water continuously.