Thanks for the well written guide. It helped me 😀

I'd like to offer two observations made while I ported an existing theme (from Sublime Text) to Xcode:

1

Even though I entered all my familiar battle-tested hex colours, the Xcode theme looked significantly different. It just had an overall washed out look to it.

Eventually I figured out that, before pasting each hex colour into the field in the Xcode colour picker, I first needed to click the gear icon and change the profile from Generic RGB to sRGB. After going through and re-pasting every colour with that extra step, the colours in syntax-highlighted code finally looked correct.

2

It seems that there is a mysterious Heading syntax identifier which isn't mentioned in your guide.

What's mysterious about it is that it comes and goes from the Fonts & Colours section of the Xcode Preferences window. Sometimes it's there, sometimes it isn't. If I launch Xcode.app fresh and open the Preferences window, it's not there. But if I then close the Preferences window and immediately open it again, it is there:

Whatever it is, it corresponds to the key xcode.syntax.markup.code in the .xccolortheme file.

-- Duncan