On 6 Oct 2018, at 10:48, Jacob Carlborg wrote:

I’m not expert on this subject but I did have a look at the “Advance Dark Mode” WWDC video [1]. If the asset catalog or the built-in dynamic colors are not flexible enough a view can do appearance sensitive work in the following methods: “updateConstraints", "layout", "draw:dirtyRect" and "updateLayer”. The current appearance can be queried using “effectiveAppearance” and “bestMatch” can be used on the returned appearance.

It’s not that I do not know how to check for these things, but the thought of adding such checks each place we use a color (as the color itself cannot encapsulate this before 10.14) is just not very appealing, as far more colors are used than one would think from just looking at the UI.