This is a free app (a pro version is available) for creating simple animated drawings that can be combined to make an animated short, a digital flip book if you will.
Frames Per Second (FPS)
As fun as the idea of creating your own animation is, keep in mind that an internet standard is 8 frames per second (fps). A 1950's-1970's cartoon is 12 to 15 fps. A Pixar movie has 30 fps. Stepping back and thinking about that for a second,
The user interface
When you open the app for the first time, you will see a sample animation that will provide you a sense of what you can do with the app. After that is completed, tap the "+" in the upper right corner to start creating your own animation. The starting page is a piece of digital box that you can draw objects on with your finger or stylus.
Onion Skinning - This process is like page after page of translucent onion skin paper or tracing paper. This helps position and edit a frame by frame animation. You can view two or more frames at ones. Dimmed frames cannot be edited however.
After creating the frames you can add a sound track by importing an audio file.
Rendering and sharing
When finished, you render it and then can export it to your camera roll or share it.