I\'ve recently incorporated MailCore2 into my Objective-C project, and it has worked perfectly. Now, I am in the process of transitioning the code within the app to Swift. I
I would've added this in the comments below the answer but there are so many.
The steps in the accepted answer worked especially using the link to the special app password for your google account.
But @RoolPaap used a different bridging header then the one I did. I used #include "Mailcore.h"
I followed this youtube video
#ifndef MyProjectName_Bridging_Header_h
#define MyProjectName_Bridging_Header_h
#include "Mailcore.h"
#endif /* MyProjectName_Bridging_Header_h */