Xcode code sense and cmd+click to symbol doesn't work for 1 of my projects

Question

I\'ve been using Xcode 4.3.1 since it came out now and i\'ve worked on many different projects since. Everything has always worked fine until this 1 new project i\'m working

Answer 1

3 reasons this happens :

1. Corrupt derived data : Solution : clean derived data folder.

2. Corrupt project settings : Project.xcodeproject -> Right Click and clean the files mentioned in g_low's answer.

3. File not a part of project target : Check if the file is a part of compile source and if not add it...