I play chess very infrequently. Whenever I restart, I take a bit of time to get up to speed. Which chess playing apps are best for a beginner? I would prefer apps that scale up in diifficulty according to a player's skill.
Back in the day, I found Chessmaster to be very beginner friendly, with a variety of AIs to choose from. It also had some instructional segments included, which were good at the time.
Now I lose against Stockfish whenever I'm looking for a good beating. I don't think it's very good for beginners, even if you constrain its skill quite a bit.
If you want to improve your skills, maybe gamezer.com is useful. It's not an app, but a website you can visit with an iphone, ipod, or whatever smartphone. It also provides skill levels.