Unless I am missing something there is no "save preset" feature in Affinity Photos for iPad. And, there is no direct integration with the Photos app.
We should be able to open a photo from within Photos, as you can in Photoshop Express and Polarr, and save the photo back to the Camera Roll with modifications and history. As it is, the only way I have found to even save a photo back to the Camera Roll is to use the Share dialog. Ineligent to say the least.
And, though it is a wonderfully powerful app, without the ability to save presets, I will not be using Affinity much. I do most of