use of @import when modules are disabled

Question

I have the following import in my code:

@import Foundation;

I am encountering the following build error:

use of @import when modules are disabled

I have seen @import vs #import - iOS 7 and I have set "Enable Modules" to "YES".

Despite this, my problem is not solved.

Unlookedfor

What is your problem? – Omission

Your question is surely your answer? I thought that you had to enable modules to be able to use @import? – Fachini

Unfortunately @import is not supported yet for .mm files or rather Objective-C++ (I tested with both g++ and clang++ as I really wanted to make this work). – Chalco

Answer 1

I got this warning in a zero-swift project whenever I tried to add the @import SafariServices; statement.

Solution: Enable the modules. Go to the Target > Build Settings and set the Enable Modules (C and Objective-C modules) to YES.

OR

Note: I haven't verified this potential solution, but probably worthy of consideration if there are side effects caused by this solution.

Rather than enabling modules to entire project, we can enable modules for a specific file which is importing c++ file. Go to build phases -> Compile Sources -> Select the file -> Add compiler flag -fmodules

Kitchenware

Thanks! worked for me. PS: you forgot to censor your target name :-) – Thou

Thanks @Thou , much appreciated. – Kitchenware

To my amazement, this didn't resolve the matter for me. Then after running out of ideas as I was sure THIS IS right, I restarted Xcode (9.2) and then it worked totally fine. Sigh. – Farmann

Xcode 9.3, struggled with same, did same, and happened to read your note Mr. Snell, quit Xcode and opened, and THAT completed the solution. (bad Xcode dog BAD :-) – Laundrywoman

Thanks Peter - I've been trying to update parse and parse/ui on an old app to move it to sashido and i was banging my head agains the wall that none of the PF stuff was working! – Lagging

Answer 2

The possible cause is that you use Objective-C++. Then modules get disabled despite the proper build settings.

Spanishamerican

I, at one point had .mm files in the project. They are no longer there. I double checked - no .mm files in project. Also, i have done everything already described in this thread. Still getting the same error. Modules are enabled on all targets. Foundation is imported. I checked the file types on all source files, they are Objective-C, not Objective-C++. Any suggestions? – Helainehelali

I noticed the issue is caused by importing the framework (with @import Foundation) into a .mm file – Tine

I am using Obj-C++, and facing this same problem. What should I do? – Forecourt

you should create an Obj-C wrapper that use @import (if you actually need to) – Ensnare

hundred times this! i removed @import Foundation from MyFramework.h and it works now! – Flannel

Answer 3

I've been mixing ObjC, ObjC++, C++, and Metal. Whenever I get the "use of @import when modules are disabled" I try replacing:

@import Name; 

with:

#import "Name/Name.h"

example, replace:

@import Metal;
@import MetalKit;
@import CoreVideo;

with:

#import "Metal/Metal.h"
#import "MetalKit/MetalKit.h"
#import "CoreVideo/CoreVideo.h"

It seems to work.

Candlestand

Thanks! Works for me too by replacing @import GoogleMobileAds; with #import "GoogleMobileAds/GADBannerView.h" – Mudd

Answer 4

Check if you are using #import "ProductName-Swift.h" somewhere in .mm files or any other files other than objc files.

Because if you use this import in cpp files then modules gets disabled automatically.

Fateful

Answer 5

If you are using objective-c++ (.mm file) and none of solutions above work, you can try the following:

• Open Xcode Build Settings
• Targets -> Build Settings -> Apple Clang - Custom Compiler Flags > Other C++ Flags
• Add -fcxx-modules flag

then build again. The error should be gone.

Credit: https://developers.karte.io/docs/setup-react-native-sdk-v2

Incidental