syntax highlighting - Xcode code sense color/completion not working

Question

EDIT: This is weird... if I double-click the Recent Projects item for the project in the welcome screen, code sense and coloring works just fine but if I just click Open (bottom right in welcome screen) it doesn't. Opening from File > Recent projects does not work either and neither does double-clicking the .xcodeproj file in Finder.

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Code sense for an iPhone OS 3.0 project I have been working on for several months (through different installations/versions of Xcode) is not working any more. For instance, if I do NSString *myString, all code would be black (no coloring, no Option + Double Click, no code completion). Code Sense only "works" for my own classes/methods/properties but not for any of the SDK classes. If I create a new project from scratch I do have all of these working.

I already tried changing the "Base SDK for All Configurations" in this project. I already tried "Rebuild Code Sense Index". I already tried "Clean All Targets".

Documentation in the Preferences is all downloaded and working. For instance, if I select the NSString above and do Right-Click -> Find text in documentation, I get the window with all the reference to the class.

Any ideas will be greatly appreciated.

Answer 1

In Xcode 4, I haven't been able to find a "Rebuild Code Sense" button either, but if you go to Window -> Organizer, select the Project tab, and click "Delete..." next to the Derived Data folder, it seems to have the same effect. (I got that tip from http://blog.slidetorock.com/xcode-4-code-sense-autocompletion-problems, which indicates that it got it in turn from https://stackoverflow.com/questions/2138047/xcode-code-loses-syntax-coloring - but I don't see it in any of the answers there. Very curious.)