^ as above – flip the wheel round (brake disc on wrong side) – if the rim stays ‘out’ to the same side it’s the fork; other way and it’s the wheel.
If it’s the fork, you can actually get away with putting a tiny bit of dish on the wheel to put the rim central without too much strength compromised, or just return the fork and hope for a better one. I have tried many different steel rigid forks and it is nice to get one that’s actually perfectly true in this regard. Shouldn’t be so hard to get such a simple item welded straight, but in my experience it’s the exception rather than the norm.
That said I currently run a spot-on set of the Swift forks on my Niner. They are very nice! Surprisingly supple and better proportions aesthetically than the Niner 853 ones I ran previously.