Xcode 11 - Instance method ... conflicts with same method from another category

Question

after updating to Xcode 11 all of my projects report many warnings (sometimes 1000+) like:

Instance method 'a_custom_method' in category from 
/Users/XYZ/Library/Developer/Xcode/DerivedData/PROJECTFOLDER/Build/Intermediates.noindex/PROJECT.build/Debug-iphonesimulator/PROJECT.build/Objects-normal/x86_64/ProductCell.o 

conflicts with same method from another category

As far as I can see these are custom helper instance methods I've created, but never had any issue like that before.

As a result of these numerous warnings, I'm having difficulty compiling and running the project.

I've checked similar older questions for this (eg. saying there may be #import ".m" file somewhere) but this is not the case for this.

Anyone with similar experience? Thank you!

Answer 1

And I found it just hours after posting the question...Following the advice at: https://stackoverflow.com/a/29805611/2681961 all I had to do is move the @implementations in a .m file. Previously I kept everything inside a .h file, but it seems the newest Xcode version doesn't like that. Oh well...