This is my color theme for Xcode. It's a bit crazy and several people have reported epilepsy symptoms after using it... so beware.
Open a terminal and type:
D=~/Library/Developer/Xcode/UserData/FontAndColorThemes && mkdir -p $D && cd $D && curl https://raw.githubusercontent.com/redcode/Code-Transfusion/master/Code%20Transfusion.xccolortheme -o "Code Transfusion.xccolortheme"