Question

This is my .pch file –

   //
// Prefix header for all source files of the 'English Club' target in the 'English Club' project
//

#import <Availability.h>

#ifndef __IPHONE_4_0
#warning "This project uses features only available in iOS SDK 4.0 and later."
#endif

#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    #import <CoreData/CoreData.h>
    #import "Helper.h"
    #import "Animations.h"
    #import "Constants.h"
    #import "SoundPlayer.h"
    #import "UAirship.h"
    #import "UAStoreFront.h"
    #import "UIIMagesNames.h"
    #import "UIView+Sizes.h"
    #import "HelpButton.h"
    #import "SoundPlayer.h"
    #import <RestKit/RestKit.h>
    #import "UIHelpSoundFiles.h"


#endif

Still it is very frequent that Xcode will give me errors that he can not find those classes. (Helper for example).
The thing is that the project will be compiled and work fine but I have hundreds of errors that disturb me looking for the real ones.

Any idea why?

Answer 1

This appears to be a known issue in Xcode 4.4 (as seen in the release notes)

It is suggested to Delete the PCH index folder to workaround this issue.

To locate this folder, in Xcode, open the Organizer and select the Projects tab, then select the project in the left-hand pane. You should see the Derived Data path for this particular project with a small arrow to Show in Finder. If you click on this arrow, you will be taken to the right location in Finder. If you then navigate to the Index subfolder and delete PrecompiledHeaders folder, you should be all set.

Xcode should re-index, and re-create this folder, but the errors should be gone.