Basically my fix was that with localization. I upgraded from xcode 3.2.5 to xcode 4 and then screwed around with built in interface builder and turned on localization for a XIB file accidently which placed my source files in en.lproj directory. After moving them back to Classes folder it worked perfectly.
It's been ages but the answer is just to move the code into a new folder and the code sense should be working now.
This happened when I added a new Objective-C Class and the code sense doesn't work only on the newly added .m and .h files (on XCode 4 latest update during this post).
Open XCode’s Organizer window, go to the Projects Tab, select the correct project, and hit the Delete button next to “Derived Data”.
Quit XCode.
在Finder中导航到项目的.xcodeproject文件。右键单击,选择“显示包内容”。
Leave the project.pbxproj file, but delete the project.xcworkspace file, any .pbxuser files, and the entire userdata folder.
Open the project in XCode. You will see XCode riding high on the CPU usage for around 10-60 seconds, depending on the size of your project. The activity window will say “Indexing”
When your CPU spike returns to earth, code completion will be working again.
There's a lot of deleting going on there so please be careful, but this definitely worked for me.
Again, for the sake of helping others with this issue which, in my case, happened upon upgrading to Xcode 4.3.
Of course I tried the solutions offered in this post, and none of them worked. But the suggestion to move the location of the project in Finder brought back some Code Sense, but the suggestions didn't make any sense.
I ended up deleting my project and re-cloned it from the git repository.That brougt back Code Sense for me...
I've been doing this, and it's worked multiple times for me (after trying all of the above previously).
Edit: Now I just hit space, backspace (the mac version) and rebuild... works nice. Then, remember to scroll (sometimes the colors don't show up until you scroll somewhere)
Find your prefix file: "ProjectName_prefix.pch".
Comment out some line. (basically change it)
Build your project, doesn't matter if it fails or not.
Uncomment it.
Build again.
I'm betting only step 2 (modify the prefix) is what does it, but these essentially get you back to running. Suddenly everything magically recolors itself and completes functions.
Good luck if that doesn't fix it, perhaps try doing this to your dependency pch files (three20 or FB api's)
I open a second project in the background whenever my Xcode's code sensing stops working (it usually works the first time i open the project but after a while code sense no longer works). So what i do is to open a second project in Xcode. Xcode will start indexing the second project and magically the code sense for my main project is back.
FYI, if one file doesn't have code sense but the rest of your project does, check that its added to a target. Once I did that I got code sense back in that file.
Clearing the "Derived Data" only works temporarily for me. I have to do it and then restart Xcode like 3-4 times each day to get code sense working again.
I found out the real cause is in the Target's Build Settings. I moved everything from Header Search Paths to User Header Search Paths and it is fixed. In my case, the framework I'm working with is RestKit.
BTW, I came up with this because I was adding another project (QuickDialog) into my project and I was curious that it is using User Header Search Paths, but not Header Search Paths. Here is the difference between them.
From this comment here I was able to debug the problem on my end, it seemed to be a bad -w flag that the clang preprocessor wasn't recognizing properly. Basically, running
in Terminal increases the verbosity of the indexer, and should help you track down issues. Open Console.app and look for messages from Xcode, the search string IDEIndexingClangInvocation helped me find them.
For me it happened simply because the file had no target membership. If the first few answers did not work for you, go to your .m file (presumably it's this file that you're having trouble with), open the Utilities view (Edit -> Utilities -> Show File Inspector) and under "Target Membership" check the target to which you want this file to belong.