Error message "could not build module 'Foundation'" - objective-c

Question

I searched for this question and could not find much help.
Error:
could not build module 'Foundation'
#import <Foundation/Foundation.h>
What is the problem?

Answer 1

I was able to solve this using the solution provided in this Apple Support Communities thread:
The real problem here is at Build Settings in the session: Apple LLVM 5.0 - Language - Modules, we should set Enable Modules (C and Objective C) to NO

Answer 2

The suggested fix to set Enable Modules (C and Objective-C) did not solve this issue for me.
What did is renaming my someFile.c files to someFile.m. Even though those files contain just C functions (that do use Foundation types), naming them .c produces this error.

Answer 3

I found that if you use some external C / C++ code in your project, you have to remove all the #import in the prefix. That's quite a headache, but it's a true problem.

Answer 4

Cmd + Option + Shift + K and then Cmd + Option + K solved above error for me.

Answer 5

In my case I had a Precompiled Header where I had includes that included <Foundation/Foundation.h> The solution for me was to wrap the include in a
#ifdef __OBJC__
#include SomeIncludeWithFoundation.h
#endif
You may also see in your .pch files something like:
#ifdef __OBJC__
#import <UIKit/UIKit.h>
#else
#ifndef FOUNDATION_EXPORT
#if defined(__cplusplus)
#define FOUNDATION_EXPORT extern "C"
#else
#define FOUNDATION_EXPORT extern
#endif
#endif
#endif
Be sure your modules are included in the right place in your Precompiled Header

Answer 6

None of the given solutions worked for me.
I have a project with mixed source codes (C and Objective-C) and the problem was given by a .c which included a shared .h which in turn included the Foundation header:
#import <Foundation/Foundation.h>
In order to solve the problem I had to perform the following steps:
In the .c that was causing the problem add as first include/import statement: #import <Foundation/Foundation.h> You can keep the same import statement in the shared header if you need.
In the project settings select the entry under Targets then click
on Build Phases -> Compile Sources. In the Compiler Flags
add -x objective-c. This will force the compilation of the C source code as Objective-C to allow the linking with the Foundation framework and since Objective-C can embed C source code this is perfectly legal.
In the project settings select the entry under Targets then click on Build Phases -> Link Binary With Libraries. Add the Foundation.framework library in the list.

Answer 7

You can try this:
In your .pch file, write like this:
#ifndef PureStandard_PrefixHeader_pch
#define PureStandard_PrefixHeader_pch
#ifdef __OBJC__
#import "A.h"
#import "B.h"
#endif
#endif

Answer 8

I have resolved by change Build System to Legacy Build System
Open the ios/PROJECT_NAME.workspace file
Then in the top menu, select File → Workspace Settings
Then change Build System to Legacy Build System

Answer 9

From this answer:
Set Allow Non-modular Includes in Framework Modules to YES in target's Build Settings
I was seeing the issue on this line in a .m file that is being built as part of an extension:
#import <Foundation/Foundation.h>

Answer 10

So I had the same problem, but the errors would for some reason not cause the build to fail, so they were like fake errors, and I made them go away by quitting Xcode, and deleting ~/Library/Developer/Xcode/DerivedData/ProjectName

Answer 11

Just rename your Objective-C++ file from *.c to *.mm.
The errors are gone that way. It handles all the imports just fine this way.

Answer 12

Use the following:
Cmd + Alt + Shift + K and then Cmd + Alt + K
Menu File → Workspace Settings → Legacy Build System
Cmd + B
It works for me.