Testing Affinity Photo on iPad pro and I'm quite pleased with the pro level of the app.
I use it mainly to paint with Apple Pencil .Here are a few notes and suggestions that I hope you take into consideration:
1- Ability to have floating panels (studio) which you can move around or close/minimize when not needed.
2-If floating panels are not possible , at least the ability to have 2 studios opened and pinned at the same time? For example I really prefer to have the color wheel panel always pinned, and not disappear when I choose brushes. That will minimize the number of taps and enhance the drawing experience.
3-The color picker that is included with the brush controls at the bottom is very practical and handy, BUT, you must click outside of it in order to close it and then start painting, opening it again, tap to close, etc. it would be ideal to : a- be able to pin it, so you can use the HSB sliders naturally while you paint. b- if pinning it is not possible, at least let it close itself as the user starts painting, without the need to tap to close it. That will enhance the workflow.
4a-Finger press-and-hold for color picker feels awkward and needs to be enhanced, the circle is way far off , I think it would be ideal that the center of the colorpicker picks the color directly underneath it, and not where the user's finger is, specially when you drag the colorpicker on the canvas, the center of that circle gives the impression that it should be picking what's underneath. If you don't want to change this permanently at least give the user the option to toggle on or off.
4b-The time it takes for the colorpicker circle to show up (finger press-and-hold) is a bit long, make it faster or let the user specify this speed in the settings.
5-Layer lock isn't working, the icon turns red but you can still draw on the layer...
6-Add transparency lock /lock/ visibilty icons directly to the layer panel without the need to click on the (...) and open another panel.
7-Add clipping mask ability.
8-Ability to hide the selection marching ants.
9-Easier way for undo-redo , the icons are really tiny, maybe a gesture, like two finger tap , or swipe..
10- An easy way to flip canvas horizontally.
11- There is an annoying white circle that appears and fades when pinch you zoom in and out while on the brush mode. I think it's absolutely unnecessary.
12- An easy way to select an area of the image with Lasso tool and do free transform on it. currently it's a bit of a hassle, Going to the selection Persona for selection and then going to Filters for Perspective transform? which doesn't work well for simply transforming a part of the painting - I think implementing a Free Transform tool that is accessible in the selection Persona is ideal.