Even simple apps usually need to store some data somewhere. When you first start out, it can be difficult to know where. I've stored tons of data in good old UserDefaults, probably beyond what was ideal with no problems whatsoever. That doesn't mean I was right, I just knew the limitations of UserDefaults and knew my app wouldn't break those. Check out this post for all the options and think about where your app is and where it might be in the future to decide.
Deciding where to store data by Donny Wals