Everyone that says "but it's insane to use assembly to write an iOS app!" is both 100% correct and 100% missing the point. It's nice to float around on the surface most of the time and ship useful code, but if you don't spend at least a little of your time digging deep you'll miss out on a lot.

I'd never try to do this in prod, and neither would OP, but it's great to see how it works under the hood.