I have been using Raycast with its integrated AI spell checking and I am completely impressed with the results. I would love to find an equivalent solution for iOS. When I look in the App Store, there are so many options and many of them are overly expensive. I wish I could find out if there is a consensus on a clear winner. One with the ability to create your own saved prompts would be ideal.
I use Languagtool which has a keyboard setting attached to it, I have a premium account so I don’t know if it is a premium feature. SwiftKey has AI (Microsoft) in it but not sure if it’s capable of spell checking.