Guys. Linux is the future. You may not see it at the moment, but you are trusting Apple way too much. What if your golden ecosystem breaks down?
The thing is that I know lots of people who would be willing to purchase this software for even more than the original price if it was available for Linux. The Linux community is not cheap. If there is a quality product that is worth it, we're gonna buy it. And I'm pretty convinced Affinity is. When I read about it, I was super excited because as a young alternative to Illustrator, Sketch and Vectormator, there would be a chance of Affinity being more modern and also supporting other Unices than only Mac OS. See, the world of Unix is so unbelievably huge, yet you are concentrating on such a tiny subset of it. The programming effort is tiny, many Unix programs are portable between systems without any modifications. Since Mac OS is practically a BSD-Rip-off, the programming effort of porting Affinity to Linux is tinytinytiny And you could be one of the first innovative companies offering a consumer-application for Linux, which would probably not only make huge waves in the Linux community itself, but also the whole industry, which will also gain you lots and lots of customers.
Unless you were dumb enough to use native Apple-APIs of course. Then you're f****d.
In that case I would advise switching as soon as possible, as painful as it might be. It will save you lots and lots of problems and lots of future pain. I can only advise you to look into Qt, which is by the way also cross-platform-compatible. Yes, I'm even talking about Windows.