kid I used Flipaclip for a little while. I downloaded it on my phone but my phone is a little bit small for art. I need a bigger space otherwise it feels like I can't breathe while I draw. I use Pencil2d for most of my animations and art. It's really simple, but it's on computers only I believe, and it had to be downloaded off a website and not the App Store.
I've tried using Photoshop to animate but it's really not what it was made for, and so it doesn't work very well.