Xcode 9 - failed to emit precompiled header

Read this if you using cocoapods in project. I just update deployment target to iOS 10 or 11 in my case after updating pods and xcode make first build success. So problem was inside podfile where I had line

platform :ios, '11.0'

and my deployment target in project was 9.0 after I change my podfile to platform to

platform :ios, '9.0'

project was fixed.

Also make sure your import of "ProductModuleName-Swift.h" is in your .m file, and not your .h file.

Finally i got the solution of this issue. In my project the Prefix Header path is not clearly defined. Earlier the path was

$(SRCROOT)/MyPrefixHeaderFile.pch

MyPrefixHeaderFile.pch is in another folder inside the project folder, So i update the Prefix Header path to

$(SRCROOT)/FolderName/MyPrefixHeaderFile.pch

Maybe you created a new target, but forgot to add this to your Podfile:

target 'Pistachio-rrzcpjs' do

end

You can try this solution. I have solved the same problem by this way.

Product > Scheme > Edit Scheme > Select "Build" on Left Menu > Find implicit dependencies

Under the build tab, check 'Find implicit dependencies':

Then make a clean and build again.

in my point of view I solved simply switch the order of import statements and build works fine.

In my case I had the same compiler error with additional errors like "Unknown type" in one of my project files, So I just added this to the problematic file, and it solved it instantly.

#import <UIKit/UIKit.h>