This app was mentioned in 14 comments, with an average of 2.64 upvotes
You can screen record using the in-game method, and then use something like gfycat to turn it into a gif. Here's the Android app, and I assume there's something like it for iOS, too.
The feature has been on android for many a version. Samsung has it built in these days, otherwise perhaps try:
https://play.google.com/store/apps/details?id=com.gfycat&hl=en
https://play.google.com/store/apps/details?id=com.gfycat
The app has an option to record your screen.
I've found the Gfycat app works really well. Just make an account. :)
I use the gfycat app.
Casper -> Gfycat app -> Reddit
They have an app. https://play.google.com/store/apps/details?id=com.gfycat
I'm using GfyCat Loops because is is easy to upload to gfycat from it.