It's mainly because I'm trying to write everything in Swift now rather than Objective-C. I still think Objective-C is a great language, but Swift is the future of iOS development.
It was easier in Objective-C as you could just rename your code file with an extension .mm rather than .m and that made it Objective-C++ and then you could import your C++ headers and use your library as you should. With Swift you don't have that option, and even the interface to C is more difficult.
Even with Objective-C there is still some work in converting data formats (NSString to std::string etc.) and you need to be careful of C++ exceptions and NSException.
It was easier in Objective-C as you could just rename your code file with an extension .mm rather than .m and that made it Objective-C++ and then you could import your C++ headers and use your library as you should. With Swift you don't have that option, and even the interface to C is more difficult.
Even with Objective-C there is still some work in converting data formats (NSString to std::string etc.) and you need to be careful of C++ exceptions and NSException.