Being a fan of coding at night with no lights but the display and the retro illuminated keyboard, my eyes were starting to grow weary of Xcode's default white theme.
Since I was already using Twilight on TextMate and SublimeText2, I searched the internets for a similar theme for Xcode. The first hits on Google led me to some versions that either had the colors all wrong (too bright) or almost no colors at all.
So I went on and made my own. This is what came out:
You can download it from Github.