I’ve really enjoyed experimenting with Looom, an animation app for iOS (App store link). Unlike other animation apps, Looom is built around a few experimental animation features, like being able to convert real-time gestures into frame by frame animation. Looom also has features that allow you to have multiple looping layers that move at different frame speeds.
This isn’t intended to be more a full tutorial, but I just wanted to help show new Looom users some of the basics of the app. For a full tutorial, check out Looom’s user guide.